The drive shouldn't be that bad at all. I made it about a year ago at around the same time, on a Saturday, and it was pretty heavily trafficked, but not so bad. I imagine a Thursday will be better.

Islamorada is my favorite place to stop for lunch/dinner coming and going. They've got a lot of nice options right off the highway. For some reason, the name of the place I last went escapes me. It was on the drive back. On the right-hand side of the road. Seafood place, but it also had a small market with it in the front. Sorry I can't be more helpful on the specifics. I'll try to find it and post it in an edit.