[Dean]

Cool. Great idea.

To relieve the stress on the seat, a cross peice of your square stock just behind the seat would help like a + or a cross. You can double it up if necessary.

In the rear, I'm not sure you need a second mount point at all. Just a friction surface to prevent left to right slip, and disperse the load.

No reason to penetrate the deck I don't think, and I fear if somebody whacks Matt's mount, it might crack the rear glass.

On the tail, just stop an inch or two short and make a T with a single peice of your square stock, or just a flat piece on the bottom either just roughed up, or throw some grip tape or old inner tube on the bottom. You can shim it to match the angle if you want.

I think I have some flat aluminum stock lying around if you want.

I think I'll make one as well.