RSW is my home airport as well and I saw them briefly last week when I flew out. I believe Jet Group has a maintenance station at RSW (on the side where the old terminal used to be and where PrivateSky still is). I'm fairly certain the 747 is a cargo plane as I don't recall seeing any windows (it was a 6 AM departure though so still dark). I would guess they are in there for a maintenance check of some sort though.