When I started to build my BP room I moved all my snakes into my incubator (which is dark 24/7). They were in there for the better part of 3 months. While in there I noticed they all seemed totally fine. They all ate normally, acted normally, didn't get sick in any way. So I just left it that way.
I have considdered putting a lamp in the BP room on a 12 on, 12 off timer. But, until I've decided 100% I'm leaving the lights off.