cage insulation?

[snakekid6996]

My room gets cold in the winter due to poor insulation and flow. I keep my snakes in aquariums, but my boas ambient temperature isn't as high as I'd like it to be, although the backing spot isn't bad. I was concidoring selling his cage (a 125 gallon fish tank with custom plexiglass top) and buying a 4X2 pvc cage to see if it would help. However, I have a nice set up with a nice stand and a top piece built by my grandpa, so I'd hate to sell it. I'm considoring trying to insulate the fish tank before I sell it. I would use either 1/2" or 1" insulation board and paint it black and cover the back and sides. Would this help much with the front being glass? I use a uth year round for the basking spot, but added a 28W radiant heat panel above it for this winter. I could also maybe insulate the bottom, but I don't know if it would make a difference, because he already has 1/2" or so of cypress mulch bedding and heat rises. So has anyone on here tried insulation boards and did they see a raise in ambient temps?