Wow, 42 views and no one replied. Darn it!!
Welcome to IRV2!
The best way is whatever way finds a buyer. No joke. So it really depends on whether you are willing to do the legwork to get exposure, and how important it is to recapture the most money back on your purchase. Anything that involves a consignment or trade in requires some funds to the seller so that comes out of your proceeds. Advertising it and selling it yourself will likely net the most cash.
So, all the things you mention can be employed. Get a classified listing here on the forum, put one on Ebay, RV Trader, your local classified ads, just get as much exposure as you can 'till a buyer comes along.
Pricing it mid-way from wholesale to retail might attract someone that's looking for that type age and size at the dealers and sees yours for a lot less. Dealers will tend to price them much over retail book, and allow much less than wholesale for trade-in. They are all about profit and are professional negotiators in business to make as much as they possibly can.
If you have a large RV dealer in your area you could talk to them about their consignment program and see if it's something you'd be willing to pay for. You can always do that after you've given it your best shot trying to sell it yourself. Or trade yours in on something they have that you like, negotiating a deal you can live with.
Get it cleaned up (detailed) as well as possible and fix any deficiencies. Get it as spotless and shiny as possible so that it shows well. Make sure the drivetrain maintenance is up to spec and the tires are in good condition. Unless you're selling it as a 'fixer-upper' people don't want to or don't think they should have to spend any money on it when they buy it.
Perhaps this will get some more discussion going and ideas that might help you get it sold.