Hi, The '73 4 door Maverick rear bumper brackets would work for your application. They put the bumper out 5/8" further from the body than the two door '73, or the earlier small bumper cars. It should give you just enough extra room to clear the trim piece. If you can not find them, an alternative would be to put spacers between your brackets and the rear panel. This would require longer bumper mount bolts, but would give you the ability to set the bumper as far out as you want it to without buying another set of brackets.
I did not know that the 1973 4-door rear bumper brackets differed from 1973 2-door rear bumper brackets. Are you sure that is right? 1973 rear bumper brackets, regardless of doors, moved the rear bumper out the same distance compared to the 1972 and earlier cars.
similar problem with my fiberglass bumpers I've been working on my fiberglass bumper, and of course I went a different route and bonded the bumper to the fender extensions. Looks good, but the chrome trim makes contact in the lower corners. Don't look that bad, but I'm open for ideas.
I have a 4 door 73, so that was what I measured against my friend's 70 two door. There was a 5/8" difference between the two, with mine sticking out from the rear panel further. I didn't say anythingabout the two door '73 because I was not sure.
The difference is one was a 1970 and the other was a 1973. 1970-1972 are all the same. 1973 has the same exact bumper, just different mounts.