Insulate the heck out of the whole thing....very well if using light bulbs, etc.
Light bulbs burn OUT often....the little ceramic heaters will too but hopefully less often. It's the humidity changes that will get to most stuff you can readily adapt to that environment.
The humidity will get to just plain old thermostats.
Read a bit here
http://www.chromalox.com/products/prodinfo/en/srl.html or google search for "heat trace" + "self regulating".
This is the stuff I routinely install for commercial or even residential water line freeze proofing....it lasts and lasts--it should see the energizer bunny into the grave even. No contacts, no t-stats, just use a plain old light switch to turn it off during warm or hot weather to save even a few more dollars cuz it does run slightly during hotter temps--just a little, but not much currant draw.
Most are designed more/less to be fully conducting around 37 to 38 deg F.
They are rated from around 3 watts per foot and up--I would say use the smallest one and not wrap it on pipes less then 1 1/2"--just tape it straight onto pipes in straight line--bigger stuff, wrap it one turn every 8" to 1' or so--follow manufacture's instructions in any case. Then insulate.
This stuff sits doing it's job outside in -20F (and way lower) weather with 4" of insulation on water/chemical pipes for decades.
But it's a bit pricey--but worth the $$.
Just a suggestion for lower maintaince/problems.
