Andrew
Great Inverter unit! As a regular camper this unit would impress the hell out of my regular camping buddies who always try to turn up with a new gadget each time. I'm not sure that with the inverter mounted right beneath the seat that you need to install any other form of heating eh? However, the low cost BigW Jump leads shown in your later photo have let the unit down I'm afraid. I tried to use mine during the last camping trip to start a friends car and ...NO GOOD!
I thought it might have been something else with the car but swapping my chepo leads for someone elses real ones started it immediately. I am not the only person to have suffered this I have since learned.
I feel sure you will not be getting the charging rates you could get with a decent set due to losses and well, actually high resistance which is not desireable in 12V circuits eh?
Just a tip.
NEVER rely on those Low cost leads in an emergency. Sometimes they just dont work.