I have over 20 years as a cutom painter and my dad owned a custom paint shop so hear me out. You most likely do not need to sand. You definitely do not need to use a DA! I didnt sand my old 92 PS when i bought it and you could read a newspaper in it when i got done. Use ONLY 3M polishing products. Others have too many fillers and will leave your job looking crappy in a few weeks. You will need 4 stages(wool pad + compound, low cut wool pad + imperial, and then waffle pad + Perfect It finishing glaze then wax). Probably 6 if you sand. You can get different cut wool pads too which should further reduce need To sand. Go to a local automotive paint & body supply store and get you some 3M compound, 3M imperial glaze and some perfect it finishing glaze, buffing pad and a pack of waffle pads. They should help you with what you need....maybe a Velcro pad for your buffer too. Makita makes a great variable speed buffer if you need one. Cover the interior, buff in shade, and i would mask off rub rail etc so no compound can get in crevaces. Id even throw sheets over rails on trailer it will make life easier when cleaning.
Feel free to pm me any questions.