No RV dealer or broker is going to buy at a price above NADAwholesale and generally low wholesale at that. That applies to trade-ins as well as outright sales - if you get a trade-in above wholesale, you are merely receiving the same discount on the purchase price you could have got without a trade.
As for consignment, yes you can get more money if the rig sells. But remember, the dealer is not going to pay for any repairs the buyer may demand nor is he going to provide a warranty to the buyer o any other "dealer" services. He may or may not accept a trade-in either, which could affect the salability of your rig. And in some dealerships the saleman's commision is less for consignments than for other rigs, so they don't work hard to make sales on them. So whether it sells at all and whether you end up with more money in your pocket is somewhat of a crap shoot. Some people have done well with consignment or with "sale by owner" listing services (e.g. rvclassified.com and rvtrader.com) while others have waited for a year or more with few inquiries and no results.