The coil I posted above is a add on that does not rob power from the ignition, it would need a battery and maybe more, I have no idea how good it would work.
Looks like those self launch wheels for kayaks. I had plastic ones on the transom for my inflatable boat with engine on it. Half way down a small hill the plastic axle twisted apart in two pieces on one wheel. There I was stranded till I found a bolt laying on the ground and make shift got down to the ramp from the parking lot. I got the bigger inflatable tires with metal transom mount to use now. Plastic has its place, but maybe not with so much weight.I was wondering what the large picture meant, then I opened the small picture and see you’re towing the canoe. What kind of wheels do you have on the rear?