A quick search shows that the Fort Meyers Freightliner Dealer is also a SPRINTER dealer, so they would most likely do work on an RV. From that contact you may find another good reference talking to the mechanics or the shop foreman. Sometimes they don't want to turn away work, but when they need to they can point you in the right direction (they want repeat business or a good reference from you anyway!).
I'd check-out any shop that works on Sprinter or small (VW, Mercedes, etc) diesel engines to see if they are willing to work on an Sprinter chassis with an RV on it if you don't have any hints from the Frieghtliner dealer.
The one truck shop I use for our Kodiak does most vehicles (just not small diesel engine cars). They also work on a lot of RV's, so it's a good fit - Found them through asking around and looking on both the old phone book and on-line. They also recommended a place for warranty work if I needed it.
I personally would stay away from an RV dealer for ANY chassis work, including OIL changes. They have the best knowledge in the coach, not a chassis.