Dave, with the car being so low and my deck attach points out a foot or more beyond the bumpers, I could crank the straps down so they were tight (really hard to get that next “click”) and yet the frame wasn’t pulled down more than an inch or so, overall, because of the shallow angle of the straps. Tight, yes.... Down, no. On the car, I strapped over the bottom torsion tube in front, and over the transaxle frame horns at the rear. What you have is way better.
Then I would take off and stop after 5 - 10 miles (or before the first interstate) and crank them tighter again (they would always go another click or two after it settled) to take care of settling. They would need no further tightening for the rest of the trip.
I was not cranking it down to the suspension stops by any means, but it was snug. Oh! And I crossed the straps at the rear only, to keep the rear from moving sideways - the front straps were straight. I only noticed the car move on the deck once, after hitting a series of potholes on a sweeping curve in Philly at 70mph, and the rear had moved to the outside about 1/2”. After that I crossed the rear straps only.
Good Luck with your “test drive”, but you’ve been pretty thorough through all this and I bet it will go just fine. My heart was in my mouth the first couple of times I hauled Pearl. After a while, it was just another drive.
gn