I'd look into a CHE (ceramic heat emitter) which you can just switch out with the existing heat bulb. Emits heat but does a lot less humidity zapping.

We have radiant heat panels in our burm's 8 x 3 x 2 enclosure, but just CHE's and UTH's in the boa and bp's 4 x 2 x 2 enclosures...

Don't feel pressured to move into a tub! You can do display enclosures with correct temps and humidity, it just takes a bit more work. =)