Brad, I'm about 2hr 45min from you. That would be under 2 1/2 with the Challenger:-). I don't think I'd be comfortable machining a little thickness of the back face of the rim. That could effect the integrity of the rim. We'll see how it works the way it is for now, then consider other options if need be. It didn`t rub when I had it out Sat. evening.
Something I learned recently.
Aluminium rims are actually built 3mm thicker than their engineered design.
Therefore it IS safe to machine 2-3 mm off if required.
It's a legal mod in Australia and our rules are a whole heap more restrictive than yours.
Brad's on to it
Had 2mm taken off the Centerline Scorpions on my challenger and 3mm taken off the Cenetrline Autodrags on my 72 Dart Swinger to make tight clearances acceptable.