There are some very good water borne acrylics which can endure the humidity. Many are bar-top finishes so they can take the beating and the moisture. You can also use marine acrylic resin (don't use polyester resin - like you'll find at Home Depot and Lowes etc.) Acrylic resin dries harder, out-gases faster, and does not have a residual toxicity. I used a combo of these products on my recent Tegu cage - the upper portions, and the entire exterior I finished with a water borne clear acrylic finish, and the lower interior portions I coated with acrylic resin to ensure moisture protection on the high moisture areas. Just be sure to allow enough time, with full ventilation, for everything to out-gas before you close it in with doors, and put your reptiles in - I would say at least a week.
MAP
Here's what I was refering to. The lower area, from the elevated pond (on the left and the basking shelf (on the right) and the entire bottom portion is resin, the rest is water borne clear acrlic.
