There's an enterprise rental in Key Largo and it's about $70/day. I think you are better off doing that than driving the RV into KW. You could park at Searstown, I've seen RV's there, but not sure how much they enforce parking, or back on Stock Island,maybe at Leo's or Boyd's storage lot, but then you will need to take a taxi into Old Town and back, so you will have spent nearly as much as renting a car. Christmas to New Years is the busiest time of the year in KW so everything is crowded. We'll be there, as usual, for the holidays.