if your only making one, u might as well go with a uth, no sense in wiring up heat tape for one enclosure.
and heat tape will heat through anything, 115 degrees or so through 5/8 inch without a helix.
3/4 isn't much different. my heat pads that ive used temporarily also heat way higher then 90. wood holds the heat well and if your using a heat lamp above, u wont need more then a foot of 11" to give a nice spot for belly warmth, as it spreads a bit.
Good luck!