If that $13,745 is truly the MSRP and not some dealer fiction, then the $11,161 is a good discount for that price range. If the dealer is advertising it that low, you can bet he has room to negotiate some too. My guess is, however, that the "MSRP" has been padded to give him extra room, so don't be afraid to negotiate for any and everything, including the finance rate. Check around online to see what others are offering that model for, even if you have no intention of buying elsewhere.
On lower priced units like this, a dealer typically makes his sale offer at 10-12% off the real MSRP+delivery costs. He may go as low as 20% if he wants to deal badly enough, but he has fixed overhead so he can't go real deep on lower priced units. I doubt if you could get 30% discount at this price level, but it never hurts to try. However, at much higher price levels you can sometimes get 25-30%.
Negotiating: Don't take the deal personally -- the dealer isn't. The rv you love is just a "unit" for the dealer, no different than any other. If he gets what he needs on the rv, he'll sell it to you. If he doesn't he won't -- no matter how much you beg, cry or scream. The salesman is not your friend, no matter how nice they are to you. He will try to get every penny he can for the rv -- that's how the game is played. So don't assume their first "rock bottom" offer is the best they can do -- it almost always never is. And don't worry about ticking them off or insulting them with a low offer. They will sell you the rv -- if you can agree on a price -- no matter how ridiculous your first offer is. The only thing you might lose with a really low first offer is some credibility that you are really interested in the rv or can afford it.