Go here:
http://www.lci1.com/images/Flyers/Ow...ideout-web.pdf
On page 17 is a simplified schematic of the electrical system. If you look, you'll see that the only "thermal breaker" is a 30Amp autoreset circuit breaker. It's probably one of the "red cans" mounted near the batteries. Look for melted "red plastic" or even for some evidence of being overheated. There should be 2 or possibly 3 12VDC circuit breakers in that general area.
I'm making an "educated best guess" that what he was talking about isn't really a specialized component, but rather the circuit breaker in the trailer wiring. And, even though it's only a $5 part, it probably would cost upwards of $150 to troubleshoot, replace and check out the system. You can do it in the driveway for $5 and a beer <wink> LOL
Let's hope that's all it is.