What are the chances that you might be able to jerryrig some kind of divider?

I don't keep snakes together any more, but at one time I did and the biggest problem I encountered was solved by removing the greediest snake and feeding him separately at feeding time. This is my opinion only, but if I were in your situation and if I couldn't jerryrig a good enviromnent with a temporary divider or plastic tubs, a rheostat or cheapie thermostat, and a UTH, I'd worry less about the snakes living together than I would about one living in really substandard temps.