You could invert the idea, as I do.
I install the foam bumper while using a GT bumper plate, then trim the plate 1/4 inch or so within the foam. This gives the foam first impact and the plate keeps it from collapsing into the suspension. This also solves the problem of the lexan being hurt [the RR rear end body suspension does similar damage on TC bodies] from impacts.
Although I like the idea of bodies that accomodate the wide bumper plates and I would imagin the areo effect could be a positive. I think some body makers actually shape their front end in the same manner you described/illustrated [I believe in the NSX body style].
BTW, good topic. Very "different" from the usual threads and posts [although very necessary since I can never remember where that piece of info I read before is now...LOL].