First, we're speaking of an electrical system that's powered by a portable
generator, right? So the "on/off" mechanism would have to switch the
generator on/off, right?

Actually, in my case, no. My cube is turning on the electrically power
pre-heaters on my plane, using the electricity in my hangar. No generator
needed.

However, the original poster is looking for a portable,
outdoors-parked-on-the-ramp solution. The temperature cube wouldn't work
for that, AFAIK.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"