Quite the predicament you got there.
1. Summit sells SS Lug Nuts, which is where I got mine from.
2. Do you have drum or disk brakes? If you have disk, I don't know if you will be able to get the hub/rotor/wheel off the spindle unless you can get the caliper (or whole assembly) off first.
3. You might try having someone weld a "lever" to the back of the studs that are spinning if you have disk brakes, and can get to the back of them, then try to break the nuts loose holding opposing tension on the "lever."
4. Do you have a brake flush kit installed? This would help keep things a little more clean (of salt) after you dip in salt.
www.championtrailers.com sells them.
Good luck.