On all surfaces there is a limit to how many times they can be power buffed, rubbed out or cut polished with rubbing compound. These all smooth the surface by removing some of the gel coat or paint to get rid of both the chalking on the surface and pitting.
An old trailer may have had this been done in the past or the pits may be deep enough that getting surface to smooth means removing a lot of gel coat, leaving it pretty thin.
That is one big advantage to using Red Max #3, or Zep wet look. They are a very thin liquid that as you wipe on each coat fills in the pits until your polish coat is smooth. typically 4 or 5 coats. But the coats go on fast. Your just wiping it on, by the time you finish first coat were you started is probably dry enough to start over.
Key is just to totally clean it first, that is where the time is invested. Bar keepers friend is just enough to get the chalky surface off as well as stains. TSP, bucket and brush to clean it some more, rinse really really well.
Let dry and start wiping on the floor wax. Couple hours later stand back and say "WOW"
I would add one caveat, if your thinking you will paint in the future avoid any wax or polish, it will all have to be 100% stripped to get a decent paint job. Even a small amount of wax residue can mess up a paint job (fish eye) and paint generally won't stick well to polish (peeling in the nooks and crannies where you did not get polish removed)
That said I see no reason to paint when my 35 year old camper that used to have all the shine of a real egg now looks pretty much like new from the Red Max treatment. This picture is a copy, of a reduced size copy, copied again to remove license
plate. In person you could ID the trees by looking at the reflection of the leaves that you can still see around the left top corner.