An RHP should do fine. You will probably want to go with a higher wattage one though to play it safe. A RHP is basically a "touch safe" CHE in panel form. If your room gets that cold in winter, you might want to think about a space heater for that room. I use RHPs in my cages now and will be using RHPs in the 3 AP T10s I just ordered as well but I keep my house around 75F so in my quarantine/glass tanks, I just run heat tape on one side and just ambient room temps. Of course its all controlled with Herpstats.
Also you might want to place a flat rock like a piece of slate or flagstone under the RHP off to the side a little to act as a heater too.
RHPs do heat the air, that is their main function really. They heat whatever is under them which in turn heats the air and they also heat the air itself just from their warmth. Generally with my RHPs, I just set the Herpstat probe on the cool side of the cage and set it for 80F/ Then let the warm side get to whatever, which is usually around 86F. Never had a problem in over 3 years. You don't have to give a hot spot of 90F as long as your ambient is around 86F. I'm not really sure where the whole 90F hotspot idea came from as both my boas pretty much hate anything over 88F and my BP only sits on her 88F for a few hours after eating. Rest of the time she spends in her cool side hide.