Honestly, I'd really stick with RPM. Having aluminum towers (even with plastic body mounts) makes the bulkhead take any impact at all. Bad landings on the rear at an angle will snap the bulkheads right off if the tower is aluminum and the bulkheads are not. Heck, even if the bulkheads are aluminum, they could snap. (integy bulks, plastic stock towers... snapped clean off!)
It affects handling, but bashing across the lawn or hitting jumps isn't "handling" intensive.
Just my .02.
If your dead set on aluminum, the rear was the one I always broke before going with RPM, but I also ran a new era 3-point roll bar which helped protect the front one.