One: A lot of people here are going to be against keeping two snakes in the same cage. I myself don't see a real problem with it, but others are going to. The stats are against it. The problem could be there. When two snakes are together, one will always be the lesser of the two.
Two: 70-75 at night is too cold, try a infrared bulb at night.
Three: If you want to up his weight/size, try feeding him every four days...it won't hurt and the worst case is he won't eat.
~Jim