On a modern car this would be a 30 minute bolt on affair, but for a CRX this is a build thread, lol.
Time to do something I've been fearing for many years, the dreaded rear CRX bumper of rust!

I made sure I had a replacement in hand well before I began this job because I knew that once you remove the OEM bumper there is a 0.3% chance it will ever be usable again, and this was definitely the case for me.
- a few screws at each wheel well corner, and mud flaps, this was the only easy part
- 12mm long head nuts, 2 inside the hatch area and 2 below behind a plastic splash shield that you also have to remove by unscrewing the plastic trim screws.
- several philips screws, 3 or so on the top under where the tail light area would be, 2 on the bottom of the bumper, and one dead center behind the license plate
for the philips screws I had to just grab them with channel locks and turn little at a time, or drill out completely.

Finally the bumper ejects itself from the plastic bumper cover and rust explodes all over the garage floor.

I found new-old-stock licence plate brackets on ebay but they were 100USD each plus 20 shipping so 220 total, but I found a universal plastic plate holder on amazon for about $14 next day shipped.
Lighter, cheaper, it'll last longer so I was sold.
I just need to source some stainless hardware for the plate cover and we're good.

The rear body where the rear bumper bolts up to has some rust, but it's not bad. Once I grind off the rust, coat with epoxy primer it should be fine, there's no holes or major structural issues.



This is part 1

 

More progress, cleaned up the rear, wire wheel on the rust to break up the loose stuff and get down to the solid bits.
Quite rusty but the structure is still solid. I'm gonna pick up a sanding wheel to get it a bit 'flatter' and then apply some rust killer. Final step will be to shoot some 2k epoxy primer to any exposed bits.
Photos showing some progress: