I have lots of experience working in such an environment. As Chris said, the swing is the biggest issue. MWSD rotate once and Twirl out of the swing. (A good swing worksphop would help.) When calling to such groups, I limit the swings to eight beats, (Replace a balance & swing, with a DSD & swing) Select your dances carefully.
Also since MWSDers are used to moving to the beat and not the phrase, I would use simple wholeset dances, like Galopede, to initiate them to the phase. Also a couple of New England style squares would help.
Another area of difficuly is progressions, so chose them carefully. Becket dances usually work well.
As a final bit of advice, introduce new calls slowly, until the dancers are comfortable with contra. There are so many calls that overlap both communities such as Box the Gnat, Rollaway, and California Twirl, that you will have lots of dances to choose from. Once you win them over, you can add calls that are not on their lists, such as Hey for Four and Mad Robin.
I am excited about your opportunity, and would enjoy getting a report back, about your success.