Hi John: I am working on a '76 Wagon that had the same issues. Remove all traces of rust with a wire wheel/disc. Treat well with a phosphoric acid rust remover. Paint with POR-15. Use an etchant primer (POR-15) over it, then do bodywork. Bondo will suffice, or fiberglass. POR-15 also makes a two part epoxy putty that is excellent for filling small areas, it dries super tough and is sandable. Repair, prime, sand, paint.

If you'd like some photos of my door repairs, send me a PM and I will forward them to you.

On your windshield washer - I might suggest you change the pump at the bottom of your reservoir. It's a reasonably straightforwar d fix, and is inexpensive. I bought a new pump from rock auto, though I believe you can get these from Autozone or the like. Good luck!

Chris

Strip the metal bare, cut out any rust, and have someone weld in sheetmetal.  Bondo is a poor way out.  I'm going to be welding in metal from Fred Morgan to patch the rot on my quarters.

I'd suggest an epoxy over self-etching primer once you have it down to bare, repaired metal.

You do not need an expensive M.I.G. welder to do spot welding repairs, check the eastwood company and you can use a panel welding tool.Or check with harbor freight for the Chinese copy.These tools adapt any 110 arc welder to use instead of a M.I.G. the British use these all of the time...Metal is always better than fiberglass for LONG LASTING REPAIRS.

Sure, metal replacement is warranted especially on flat panels where holes can form, especially at corners, and should be done. Sometimes metal repair is impractical, but in places like doors where you have complex shapes/intersections of panels and welds, rust can create unusual holes that are not easily repaired by sheet metal patches. I stand by my suggestion as well; certainly I appreciate the integrity of metal but in an ideal world, it can't always happen, because of complexity and cost concerns.
A poor way out? Repairs are only as good as the repairer. A well planned and executed fiberglass/bondo repair will maintain long term integrity on the cheap. Bondo that has fallen out is a sign of lousy preparation, not a fault of the material.
Reread the op's message - the first thing he suggested was a "tight budget". That says alot, metal repairs are more involved/expensive, especially if your skill level and tools can't meet the challenge.
Chris

Chris, you get a thumbs up and a "Like"