My dumps literally always stay on the one side..... I think 20g is good enugh.
i bought a 60watt likgt bluff got both with a heat lamp to heat up their tanks. Dump yes aren't really climbers but when they are they climb on the logs I have in their if I bring that all close together I think they will be happy that they can climb from branch to branch and be happy. All they do is climb the logs and bath in the water dish.