...to that right side rear bushing nut.

There is a 1" hole on the bottom of the bushing mount (aka "bucket"). While it's off to replace the bushing, I cut another hole on each side of the existing one with a 5/8"metal cutting hole saw. Then I roughly smooth out the resulting "oval" hole with a file.

With the car down on all fours, I can get a 3/4" box end wrench up through the widened hole and onto bushing nut and tighten it (a flat at a time) to my satisfaction (local specification).

IMO, that slight "modification" does no harm to the bucket. I have done several that way over the years with no problems noted. I even "altered" one much more severely to fit the exhaust on the V8, but it was still doing fine 6 years and 100K+ later when I sold the car.