Well I wasn't able to get out to the store tonight because I had a lot of work to get done, but I went online to look at heating cable and noticed a wide variety from 15 watt to 150 watt. I've never dealt with heat cable before, and I'm assuming 15 watt would be enough to get the job done, but I can't imagine what 150 watt would be used for so maybe it doesn't get as hot as I am thinking? If anything though, I'd want to get a little extra just in case and just regulate it with the thermostat, but I'd like to know how hot these things get first.

I haven't purchased the stacks yet, but I can't imagine not being able to fit flex watt in there, I'll see what I can do and might be buying some of that instead.