"pretty oxidized" been there, I fought it for years, polishes, light compounding, waxes, finally threw in the towel last fall. Read every article, watched you tube, asked for advice. . . . Finally washed the boat, Bought the sandpaper ( 3 different grit), got a bucket of soapy water turned the stereo up and went after it.
Sanded that fiberglass till I was too sore to move. Went after it the next day with my Harbor Freight variable speed wheel and some 3M polish / wax and called it a deep shine boat. Added a topcoat of polymer polish for good measure and called it a day.
And on a similar note, I'd like to add that although it doesn't last more than a month, Woody Wax is the **** for non skid areas like the swim deck. Spray a mist on the surface, mop it around with a dab of water added, let er sit 30 minutes and hose it off.
Shines, resists dirt and stains and gives the deck a non slippery feel. G00D stuff, and too easy.