okay, so here's how not to do it... don't try this at home.
actually, the fundamental concept has promise but i'll be uprating the materials. instead of one layer of 2x6 i'm now using 3 layers of 2x10 in back, and 2 layers in front. the 2x12 'keel' section was too long, and is being shortened to somewhere in the neighborhood of the bellhousing -- and mounted to the bottom, not the top.
those small pad parts have holes to capture the donute to prevent lateral and longitudinal movement. key dimensions for this fabrication are the 29" MAX outside-to-outside measurement on the wheels, the size of the inside of the UHaul ramp. the bottom of the wood parts must be at least 10,5" above ground level to clear the wheel well intrusion into the truck bed.
in case you were wondering, those are Harbor Freight wheels rated at 675 lbs each.
i'll post updates once i've got the next version constructed and holding the car - hopefully tomorrow. soon as it's dark i have to revert to packing and housework mode. the house is on the market and "priced for quick sale." one rent-a-house we were looking at in PA got rented before we could complete the deal, and another guy isn't responding so i think that one's not happening either. so the panick level is starting to set in a little since we NEED a place to live back there and don't have one yet ...