Thank you Dr. Steel for your time and suggestions. Very aware of that Showboat loader too.
Your use of safety lines certainly gives me some very good ideas for my side loads, might just have solved this!
Once the front of boat raised and set on the front bar and extension, if I run a loop over the boat and tie/attach to bar on each side...like you suggest on your Showboat, then I should be able to safely get the back end up there without the front walking left or right on that slippery front bar. I think that's my answer right there!!!
Once up, then from the rear, I walk the boat into the four Yakima canoe brackets and drop the top rail of the upsidedown Revo into the brackets, once there, its locked down and can't move left/right/forward/backward.
Usually this side loading is no problem in normal conditions, its when windy, or vehicle on uneven roadside parking, tired after all day fishing, (all of these!) where its not the best of conditions. That's the ones that will get you. Just recently I found myself in a bad situation, on side of road, traffic passing kinda close, had to load on offside, ground was lower and my truck is tall ! I had to summon Superman hero strength at last minute when I almost gave out, haha.
That's why I love these forums, one idea sparks another!
But keep the ideas coming!