...which reads just about like Ospho... for the entire trailer, but get galvanized rim wheels to go back on the galvanized hubs. (and one size larger... for Baja roads).

I think if I put waterproof grease between the hubs and the wheels (not on the lugs) I probably won't have a problem in the future, when I need to remove the wheels again. Does anyone see any issue with doing that... a bit of axle grease between the wheel and the hub as a protective barrier?

And Ospho or One Step (both acid based "rust converter" products), should be sufficient for the entire trailer itself.

What started as an axle replacement project is now just a wheel/shock replacement project. I'm also going to replace the U bolt hangers... just seems like a good idea.