I use a truck bed rack for my daughter’s kart on a trailer (Your Tow Vehicle, looking for recommendations - #45 by dodo). I just make sure the straps loop as close to the rack rails as possible, so there’s minimal leverage for bending anything. I also make sure the front strap and rear strap are on opposite ends. This has held very well, and hoisting it up there has been very easy. I don’t imagine this is much different than working on a roof rack vs. my trailer rack, BUT, I would absolutely hate having to remove the motor each time. More specifically, I’d hate having to realign my particular engine mount every time since it has proven to be extremely finicky.