rhp size questions

[snakekid6996]

I'm hoping to get my first amazon tree boa soon. I'm currently in the process of deciding on and buying the enclosure and set-up. I'm going to start with either a 70QT or a 116QT tub then sometime in the next year or so upgrade to a 2' cube pvc cage. Anyways, my question is should I get a 40W or 28W radiant heat panel? I was thinking I should buy a 40W, because they are the same price and my room has poor ventilation and gets cold in the winter (low 60's at times). However, it also gets hot in the summer and I don't want to over heat the enclosure. yes, it will be set-up with a thermostat, but I'm afraid the cool end will be to warm and there may not be enough of a temperature change for the snakes to choose from. I've never used a radiant heat panel, a tub, or a pvc cage before so I wanted to see what You guys think. Also, a baby amazon tree boa would be fine in this size enclosure as long as there is enough cover, right?