Oh gosh- I really hate to put a hold on a person's dream, but.......

That's a really big environment for just a wee baby boa!!
Is there something smaller that you could use for this little guy for the first approx two years?

I have my boas in 3x2x1 RBI reptile cages and they work really well. I have them heated with radiant heat panels. Temps are set to about 90F and the humidity is 60% and the ambient temps are around 80-82F.

One of my boas is a bit over a year and another is coming up on a year old and I can see that I will be switching them over to the AP A30 cages (4x2x6) in another couple of months. My other boa is just a wee one so I'll wait another year to switch her caging.

Boas grow slowly relative to ball pythons. They really like climbing (at least mine do) and so having some height and climbing branches is a bonus!

I also wonder, with a tank that deep, how the heck you'll get this guy in and out when he becomes large. Boas are notorious (I've read and have been told by several boa owners) for showing their displeasure at having to exit and re-enter their enclosure. I just can't imagine trying to wrangle your guy out of a top-opening space....but that's just my lack of knowledge I'm certain. I also wonder how you'll be able to keep a very strong snake from pushing through the top of the tank and getting out.

I guess you have a different environment set up for the boa for tomorrow...?

I don't know....just my initial thoughts. I'll be interested to read what other more experienced boa owners have to say about this topic...