That's pretty cold for your BPs. I don't really like to see my cool side dip below 70, and try to keep it at 75 normally. 75-80 as your hottest temp is basically what the cool side should be. Add some more heat to the tanks, whether UTH or bigger bulbs that can stay on night and day. I heat my snake room to keep my cool side from dropping below 70. If you still have issues getting the temps up I suppose you could move them to the bath room. I just worry about the possible fumes and the humidity. You shouldn't have a lot of fumes in there given you probably don't use hairspray, but cleaning supplies give off fumes even when you aren't using them.