I don't know how much work you're prepared to put into this. To do it "right" you'll need to remove the ports, take the plastic off, remove all sealants and gaskets, and get the aluminum back down to it's clean self. There's a group: http://www.hatchmasters.com/ that might give you some feedback. It's possible to send the whole thing to them and have them "rebuild" the parts; however, they might just give you some feedback on their "professional" view.

I'm not a fan of exterior powdercoat unless you really get back to orginal factory conditions and do it right.

I'd probably tend to use an 2-part epoxy or awlgrip-type paint after carefully preping the aluminum. If you can do the ports in place (assuming they don't leak), it would a lot easier. If you have to reset them anyway, it[s a different story.