No rocket science needed - basically treat it just like your car. Any quality car polish/wax will do a good job, as will any marine polish/wax. Polishes with "RV" in the label are probably just that - relabeled car or boat polishes. If the finish is in good condition, a light duty polish with a built-in "wax" (most are synthetic 'surfectants' these days) does the trick. If grimy or oxidized, you will want a more heavy duty polish (more grit in the polish). You can apply an extra wax-only coat after polishing if you like, but it's probably not necessary in most cases. Be cautious bout "polishing" the decals - some of them are porous enough to catch the polish inside and get hazy because they don't polish out. And decals don't polish up anyway.
Use of an automotive-type wash product will avoid stripping off the waxy surfectant that was applied a part of the polish.
I don't recommend ever using a pressure washer on an RV, primarily because it is very likely to push high pressure water into places it doesn't belong, e.g. around slides and into the fridge and water heater access panels (vents). Further, extreme pressures (some washers are 2000 psi or more) can cut or wear the the softer components, of which there are several. I would not, however, expect it to damage the fiberglass surface and wonder if the shine on your rig was some heavy wax coat intended to cover up previous surface damage. A 2014 vintage rig should still have its factory shine, even if never waxed. Regular washing is usually sufficient to keep most fiberglass RVs looking good for several years.