Well....
It's in park!
My Dad and I (and the wife too) modified the bracket in the way I described above. We were able to get the pawl far enough to the aft that it now seems to reliably engage park. I cannot turn the trans with either the driveshaft, or the wheel. Seems fairly solid. I just need to run to the parts store and grab a filter/gasket and a few quarts of tranny fluid to see how well it holds on the ground. I'll still use chocks to be sure it does not roll, but I think I've got a winner here!