Neonates (not hatchlings, boas are live-bearers) do need 90% or higher humidity. In the wild they burrow under moist ground or leaf litter to hide during the day, then they hunt at night.

BRB's are easy to keep if they are set up correctly. The problem comes when people try to keep them in tanks like corn and king snakes.

I run mine at 86*F basking spot, 75-77*F for the rest of the enclosure. They will put as much or as little of themselves on the heat as they need to digest. It is possible to run them too cool and kill them.