It can be done!
Less than 24 hours after taking delivery of my AW 1M, I can confirm the Curt 11184 135i hitch can be mounted to the 1M.
A couple notes:
- The rear exhaust had to be dropped off the two rear hangers in order to move the hitch into position.
- Clearance to the muffler is tight, ~1/8". I used a couple washers on the bottom mount bolts to increase that to about 1/4-3/8". A test drive before reattaching the rear bumper cover revealed no contact between the muffler and hitch with this spacing. I used one washer on each of the top mounting bolts as there's not enough thread for two.
- The driver's side inner exhaust tip has about 1/4" vertical clearance to the crossbar. It's tight and I've only heard it bang once when I went over a jarring bump at speed. I plan to put some sort of padding in there to dampen the contact.