Yes Duk you are in the swim with these ideas but off course it has all been done before and probably the best approach is a space frame front end but how far do you want to go? Why stop at half a space frame?,,,I think you know what I am saying.
As for the pedals, well, all you have to do is look at a 105 for the answer. Have them come up from the floor as you have covered already.
Nothing in local rules say that you couldn't do all these mods and still compete in AASA comps. Look at the rear
engined Sud for example being campaigned here. The ex Jim Nielsen Giulietta comes to mind regarding a "hybrid" approach along the lines you are raising although it is more to do with weight saving from what I can recollect as it has the original firewall from memory. Perhaps Jim will clarify it for us..