Not sure if you know, but most snakes do not require UVA/UVB lighting at all, since they're normally nocturnal and get calcium from the bones of the animals they eat. The reason I mention this is when I got my first snake I had both a heat lamp and UTH - but because of the heat lamp and the screen top that this required, it was very very hard to keep humidity high enough. Natural lighting and a (mostly) covered top will help you if your boa starts to have problems shedding. My snakes are all in plastic caging now with outdoor rope lights as lighting when I want to look at them, and UTH primarily for heat.
They are awesome pets!
-----
Lauren Madar
www.ophidiagems.com
1.1 Hog Island Boas
1.1 Hypo BCI
0.1 Sarong-type GTP
1.0 Normal Ball Python