I have! I had the same Surgery, L5 to S1. For me it was about 7 weeks. We drove 2 Days from Louisiana to Illinois. We stopped every 1 hour to 1 1/2 hour, and I was fine. We did split the Days and spend the Night at the Hotel. I was wearing my Back Brace the entire time. I had 3 Back Surgeries. This last one was because I damaged my Spine below a previous Fusion due to a severe Fall.
I can only speak from my Experience, but I would not fly so short after a Fusion. Things to consider are that you have to drag your Luggage around, long walks from and to Terminals. Very small Seats, flight delays, etc.
Knowing Airports and Air Travel, even short flights, it was not an option for me!
Hope this helps. If you have any more Questions, please feel.free to ask.
Good Luck to you, and a speedy Recovery!