I've always had a personal issue with aspen leaving boas too close to the heat when they burrow. Whenever I used aspen I always put a layer or two of newspaper under it so it would create a more radiance of heat and not leave the boa exposed to the heat source so much.
As long as the uth you use will allow the temps to compensate for the low room temps, sure. With my daughter's rosy boa (which is the only boa outside my snake room and in a tank) I used a smaller uth on the side to boost up the ambients and that's worked pretty darn good for us.
Boas are extremely curious and will use anything you put in there
And so the addiction begins...
lol