Just my .02 but I think I'm going to have to agree with everyone telling you to use a quality product. I would highly suggest you visit a local Paint and Automotive supply shop that is a jobber for the local body shops. They will likely have several people on staff who have sprayed catalyzed product or single stage acrylics and can tell you what will work best for your situation. The problem that your going to run into is deciding if you want to do the work yourself or have someone do it for you? I would strongly suggest you do it yourself for several reasons.
1: Do you really want to load up that mast, haul it off to a custom paint shop, pay and arm and a leg, wait several days before you can pick it up, and then risk damage while transporting "soft" paint?
2: If you already have a compressor of a decent size you can pickup a very usable generic gravity fed HVLP spray gun for about 75 bucks. A quart of reduced and flattened ready to spray acrylic enamel(which is a lot more than you'll need but probably the smallest they will sell you the way I described,) should only set you back around 30 bucks at your local automotive paint jobber and will give you a professional finish and durability that will far exceed anything you'll get out of an aerosol. You'll also end up with a lot less unnecessary product on your mast which while minimal, is a good place to reduce weight.
3: When you finish this project and see how awesome it turned out, you'll wonder why you waited so long to start spraying things the "right" way. You'll also have the tools and confidence to tackle other projects that may have seemed like a job for someone else before. Just make sure to spot prime the bare spots, final sand, and wipe every thing down with a good solvent based wax and grease remover. Good prep will make every paint job better regardless of the product used.
Best of luck with whatever you end up doing.
Actually we just got the gun and will be using a product from Interlux called Britsides. I am not set up for the two part and knowing my neighbors once I start that I'll the AQMB knocking at my door.
Let me give you the breakdown on how I got to this point.
1.) Scraped off all the stickers and the crud they leave behind.
2.) Coment clenser, a Scotch pad, and the hose. Once I had the epoxy work done to patch the holes the whole mast was cleaned using this.
3.) After we hosed it it down we washed it again with with dishsoap and water.
4.) Then we went to work wet sanding with 180 - 220 - 400.
5.) Repeated steps 2 & 3.
