On a smaller 'engineering' note, I'd add that once all set up and cinched down, that I used to use actual steel-cabling to be my 'safety chain'. And since the bike moves with the ramp (i.e. doesn't really move), it's not an issue the lack of flexibility. Again, I had measured out what the steel cable length should be after the Bike is cinched down for travel with it's tie-downs and added it after all that (and as my SafetyChain effectively... just didn't trust any cloth, new or not).
Bummer all the bad news here but it's LIFESAVER stuff ain't it?!?! Further, they've ALSO protected your liability. As a non-Engineer I was "ready to convict on your opening statement"... it was well-thought-out, cogent, and covered all the bases in MY BOOK. Fortunately I've never lost anything out of any of my Trucks ever, but I mighta been lucky carrying my CR250R the same way on my Rodeo and Scout. I mightta dodged a bullet there to be sure.
As far as the On/Off Loading the scooter on the ramp, I'd just buy/find/craft a ramp that has 2 pegs on one end to drop into the Ramp holes i drilled and then just roll it off. That is, unless you have FORTY-FOUR INCH SUPER-SWAMPERS ON YER PICK-EM-UP-TRUK!
Take heart, you just learnt a lot for FREE!
As did I...