Couple of suggestions.  Take a bunch of pics and post them to a free hosting
site, such as http://photobucket.com/.  Also write a complete, and lengthy,
description of the unit and the accessories it has, scan it and put that on
the hosting site.  Then put ads on RV selling sites, such as
http://www.rvonline.com/, with a link back to your hosting site.

People like to see a lot of pics, and read detailed descriptions when they
are contemplating spending that kind of money.  I know when I was looking
for a DP, I just skipped over the little short ads with a couple of pics
that said "call for details"

The other thing you could do depending on how desperate you are, is to put
it on a consignment lot.