I have a light tan coach too.
I wax the sides, front & back twice a year with Mequiar #56
I use #67 or #83 on the roof, and the #56 on top for effect, but not required.
If I see a tough stain like what you are seeing, I will use the #67 or #83 on sides. I use DA Polisher as I really got good with it.
The part that may make the most difference with the compounds is the pad used, rpm speed. Drives me nuts that pads come in all kinds of colors so it is can be hard to get the right one for your needs so you don't over do it.
But whatever you do. BE SURE TO WAX AFTER USING COMPOUND to preserve. For 90% of the coach I even use the DA polisher to apply and remove the wax.
My coach is 4 years old and I have waxed it exactly 8 times. I love your decals, so curious to know what you have been using on them? I have been use 303 but some wax does get on them.
2019 Sunstar 29ve; Toad Lincoln Navigator; RVi Brake 3; Roadmaster Nighthawk 676; Sumo Springs; Safe T Plus; Onan EC-30 AGS; Vmax 250ah AGM; T-Mobile Internet; Southwire EMS 44270/34951 Display 40301; Jet Flo Macerator; Alpine SPE500 Speakers; Visio M21D-H8R