RE: How I reinforced the Tamiya DF02 (Rising Storm) Chassis
Interesting mod, and the great thing about having true hobbyists involved in this hobby is them trying to figure out a better mousetrap and fixing what ails them on their own instead of just needlessly complaining about any specific vehicle design.
Ultimately it comes down to the fact that any reinforcing of one part transfers the inherent stress and force from impacts somewhere else in the vehicle. So while your fix might keep the highpin mounts from breaking off the diff case, chances are something else will break (as something always HAS to give). So maybe it's be a cheaper part that breaks, instead of leaving you with any entire chassis plate to replace. Personally I would have started by filling in the little voids with some sort of plastic epoxy, being as the problem really is that the hingpin brackets don't have much material holding them in place.
It'll be interesting to see if your "fix" works, but the problem(s) I see are that with the hingpins attached that too hard of a hit (which is what's snapping one side or the other of the hingpin mount) on either side of the cars will snap off the entire front end, and that I don't really see that extending the hingepins and reinforcing then with a few extra millimeters of plastic is going to help much if any.
But who knows, it could be the fix you're looking for. Keep us updated. Good luck.