I understand your desire to get it on the road. You are not restoring and maybe never will. Here is the plan for that. I am going by what your general goal is for right now.
1. Wire wheel and/or needle.
2. Get some cans of
this.3. Then spray with rustoleum black enamel cans.
4. This will be adequate and touch ups are easier.
5. Rattle can is the way to go here. Cheap, easy.
6. Stay off salty roads.
7. If areas start to re-rust, do 1 thru 3 in those areas.
8. Nothing wrong with this method and it can be sandblasted off if you ever decide to upgrade.
9. Regular undercoat is hell to remove.