Gregg:
Yours looks very stout and well engineered, as always. I'm just trying to make mine a little simpler in terms of fabrication. In your undercarriage photo, the shock mount crossmember is located just ahead of where your down-bars go through the bed.
My plan is to weld and bolt a piece of 1/8" thick steel (approximate dimensions of 18" x 36") between the wheelwells, and right above that shock mount crossmember. My down-bars will be straight pieces, no bending required. The welding will be done on the topside, and it will be bolted through the bed floor and through that crossmember.
Then the down-bars will weld onto additional feet (maybe 6" x 6") that will be on top of the larger sheet.
It will be easier for me to fabricate, and I think will provide plenty of strength.
I still have a receiver hitch below the tailgate if I need a push-bar. For the time being, no parachute would be needed. I'd look kind of silly dragging a parachute along the ground.
Steve.