I agree with the previous posts regarding the trim. On the APU, all 72's I've ever operated had the APU air inlet in the MLG wheel well and the system was weight switched to the left MLG. You could not operate the APU inflight because of the weight switch, reduced air intake and the potential for a right MLG wheel well fire if there was an exhaust breech and proximity of the hydraulics.
I'm not familiar with any mods, but sure would be interested in hearing from operators who do.