Paul, I'll throw my 2 cents in. If you have a trailer place around that builds utility trailers, stop in and see if you can buy a gallon or so of their trailer paint (or visit a Sherwin Williams). They will have a little bit higher end metal enamel than the valspar stuff for not much more money. The last pipe fence I painted used low gloss valspar and it lasted about a year and was faded and not looking good at all. As far as the cleaning, my last restoration ( a 79 jeep cj7) I pressure washed the whole frame and then wire brushed the frame with a wire cup on a 4-1/2" grinder. Shot it with the Rustoleum industrial grade low gloss stuff that they sell at home depot. 5 years and lots of black dirt and water later, its still on there. lost some shine, but no rust. as for the 26 gallon air compressor - shot the whole jeep, including the base/clear paint job with a 20 gallon 5hp coleman job. just use a large (3/8") air hose that is as short as you can get away with. Air guns need CFM, not just pressure. supply that gun with air, and take breaks periodically to let it catch up. Also, go to harbor freight or similar and pick up a few $3 inline disposable air dryers. its worth the money. take your time. the quality of the paint job is not just in the paint or the painting. your success will come from the time spent in preparation making sure there are no contaminants - oil, grease, water, etc.
good luck.
