Boa Questions

[AbsoluteApril]

My main questions right now are if a day/night cycle for heating is needed,

No, not necessary

and do they need light,

No, not necessary (same as with any snake)

or can they work with a heat mat alone like BPs?

Depends on the caging and set up. I have a snake room where I can keep the ambient temps up and then I use heat mats or flexwat heat tape to provide a warm spot.
If you have low ambient temps in the room, you'll probably need multiple heat sources (lighting or a radiant heat panel) to increase ambient and then another to provide the temp gradient.