Even though the MF website says the Sparkfun is compatible, it doesn’t show up in the MF connector. Looks like that was a waste of time and $20.
So it looks like if I want to use my 500.00 RealSim GNS, I have no options for using SimVim or MF to setup any other components with a 2560 without flashing over the RealSim 2560.
The LeoBodnar BBI-32 so far has been my only other peripheral option to work. I can at least create switches with it.