I agree with Liberty Man.
If you want to keep it nice over the years, use a cover.
Another benefit is RV's like to suddenly start leaking. If it's got a good cover on it, you wont be surprised by a rotting mess in the spring and will hopefully find any leak druing use - before it's catastrophic.
Dealers dont keep anything around long enough to care about protecting them so that's not any argument.
BTW, there's almost nothing a dealer does that I would do.
This is what my 2004 Wildcat looked like after 13 years of covering (and waxing every year).