UTH with dimmer switch?

[bcr229]

Personally I never put anything with electrical connections inside a cage if I can help it. Too much chance for it to get wet and short out.

FlexWatt / heat tape should never go into the enclosure as it's not safe if wet. There are sealed heat pads that are designed to go into enclosures with a thick floor that wouldn't transmit heat from a UTH, but they are outside the OP's budget - and they still need to be on a t-stat.