I put the insulation on three out of the four sides of the tank and then cut out a piece to lay over the top with a circle cut out for my heat lamp. The temperature increased--only now the temp is about the same on both the warm side and the ambient side (about 80 degrees). I'm hoping overnight the warm side will increase a bit more or I'll be in the market for a little space heater.
I did end up using tape. Honestly I'm not too concerned with the aesthetic of everything as long as my bp is warm enough.
If your temps are staying in the low 80s you're fine as long as a hot spot is offered to aid in digestion. Many keepers use ambient temps in their snake rooms (really only makes sense if you have multiple snakes) and only offer a hot spot.
Just wanted to thank everyone for the help! The temps are much better now with the warm side being around 87 degrees and the cooler side around 80ish. I can tell my noodle is much happier because he even came out to explore for a bit late last night. (This is normal for him, but the past few days before that, he hadn't come out of the hides at all--I'm guessing because he was just too cold to move.)
Easiest fix for now is 2 large heat Mats that cover 95% of the tank floor. One set to 90 and the other to 80... CHE’s are going to kill Humidity idc what you insulate with. Its a Pain. At least your snake will always be warm no matter what if the floor and hides are proper temps. This is all we had 30 years ago and snakes were healthy.