Getting back into snakes... Need some advice

[Chaos-n-Dissonance]

Sorry in advance for the long post, have a few specific questions but mostly just looking for general advice or feedback. tl;dr at the bottom for questions if you don't wanna read this essay.

So without going into a long history of my past, I used to own quite a few snakes. I lived with my girlfriend at the time, she had a lot of colubrids and a few smaller boas and I had an adult burm and a few retics. I actually planned on breeding the retics, but never had the chance. Laws changed in our state (Ohio), we broke up, long story short I no longer own any snakes and haven't in many years... But here recently I've been wanting to get one again, I just miss those quirky little buggers.

There are 2 snakes I really want. A moonglow (Carmel axanthic albino) carpet python, and an amazon basin emerald tree boa. I have ~$1000 to spare, could probably spend $500 on a snake AND enclosure/necessities. Neither of those are possible, especially if I wanna keep some money in the bank in case of emergencies.

So here's my plan: Start with basic ball python morphs, and work my way up. Since I have no experience breeding (Just a lot of theoretical knowledge), I figured balls would be a good place to start so I could learn the basics of how to breed, incubate, etc (obviously there are going to be differences between species, but there's the most documentation on balls so I figured they'd be best to start out with). Hopefully after a few generations I'd be able to afford some of the base morphs of carpet pythons (and carpet python enclosures) and move on to those, then many many generations down the line have made enough to afford an ABETB (and an enclosure that can meet all of their strict husbandry requirements) and end up with a moonglow carpet. Definitely a long process that I don't see finishing this decade, but it sounds perfect for me.

I don't want to make it sound like I'm only interested in ball pythons for the money. I'm not, and definitely have no intention of making a living off this. I do want a few of the higher end morphs tho, so if I can get there in the long run and have my hobby pay for itself along the way then that sounds perfect. I've always been interested in breeding snakes as well, and ball pythons sound perfect for that (With the largest market I'd assume they're easier to sell than say carpet pythons, which altho still popular is a much more niche market). Money for me is tight. I love my job and couldn't imagine doing anything else, but the pay isn't amazing... Which is fine for every other aspect of my life, but if I want to own some of these higher end morphs or rarer species of snake then there's no way realistically I'm going to be able to afford it without making huge life changes.

So enclosures... I also plan on doing all the enclosures DIY, and maybe selling a few enclosures along the way as a side project and to help me get to my goal. And that's where I'm stuck right now. Like I said, my budget is kinda tight and I want to keep some money in the bank for emergencies (both regular emergencies and in case I need to take a snake to the vet or something). So right now I can get a ½"x4'x8' piece of PVC foam board for ~$70. If I use every inch of that board, I can make two 36"x18"x12" enclosures. After adding plexiglass and finishing touches, the total for both cages would be a little over $100 total, which is awesome. The problem is heating. Since it's ½" PVC, I'm not really comfortable just slapping heat tape on the bottom (attached to a thermostat ofc) since I'm not sure it'd be able to permeate through the PVC and ~2" of substrate without damaging the PVC. I also don't want to attach a light fixture on top of the enclosure, since then I wouldn't be able to stack them (and being able to stack/expand is important). Radiant Heat Panels are an option, but RHP's for both enclosures would cost more than the enclosures themselves. Adding an internal Ceramic Heat Emitter is also an option, but the footprint of the CHE + protective cage (to keep the snake from touching it directly) is fairly large in an already debatably small enclosure (36"x18"x12" is slightly larger than the tubs Freedom Breeder recommends for adult BP's, but only slightly). Cutting out a ~3/8" foot long strip along the bottom to attach heat tape and only leave 1/8" of PVC to penetrate sounds perfect... But I have no clue how to do that, nor do I think I have the necessary tools. Anyone have any thoughts/insights that could help me out here?

Option #2 is to just go all-in and make my own rack. I could then buy tubs or make my own "tubs" out of thinner PVC to avoid the ½" of pvc heat tape issue. It also gives plenty of room for expansion, and I'll have to build a rack anyway here in a few years to house my first clutch. It'd also let me start out with a small enclosure for a baby ball and move it up as it grows (Where just building a 3x1.5x1 enclosure means I'd have to put a lot of decor in to keep a baby snake from feeling exposed). The problems are that for a few years I wouldn't have any other snakes, so I kind of want a regular cage for optimal viewing... And on a more technical side, I'd either have to wire each layer of the heat for the rack separately or end up with a lot of heat on the rack that isn't being used (If I make a 6 layer rack and only use 1-2 of those layers, there are 4-5 layers with heat tape and nothing on them). It's also a bigger investment up front, since I'll need significantly more materials. I could get around the optimal viewing part with a nicely built custom tub, but that'd require working with ⅛" PVC, and I'd have no clue how to work with something that thin while maintaining structural integrity. Anyone have any thoughts/opinions on this?

Also, I'm a bit worried about the PVC itself. Home Depot called it "PVC Foam Board". I've read a lot of differing information online about PVC for snake enclosures, from it's the best material to use period to it's going to kill your snake and everything else in the room. I'm guessing this is because there are many different types of PVC board. Anyone have any useful info here? Types to look for, types to avoid, or even just a resource to differentiate between everything and their basic qualities without having to spend weeks making myself an expert on PVC?

tl;dr:
1) I wanna make a 36"x18"x12" enclosure out of ½" PVC. How would I make heat tape work with this setup?
2) ⅛" PVC board... How do you work with this stuff to make a sturdy tub-style enclosure? Or would I be better off with a different material?
3) Any tips/tricks for making your own DIY enclosure? Pretty new to DIY stuff so only know the basics about materials and techniques.
4) What types of PVC are safe to use for snake enclosures?