Lots to pull apart here. The FL home is a personal decision you have to make for yourself. Don't forget your taxes on a sale! This is a situation where you need to run a few scenarios and see how the numbers shake out.
Sell vs. Rent (and the tax implications of both). I'm a fan of using HELOC or LOC if you have the equity. I used a LOC to build a 12 site RV park in a small town, opened it up and 1.5 mnths later, I'm full occupancy and servicing the debt (some of it at 8.75%) & cash flowing. Just foced on long term RVer's, no transient.
Cabins are a different beast, I have 10 at another campground I built- Broad River Campground located in Mooresboro, NC (Has Cabins/Domes/RV Sites, Tent Sites)
Cabins are sexy to talk about for sure, but you are now entering the hotel business my friend. The OUTDOOR hotel business. Not only do you have to do all the things needed for the inside, but you also have the outside to worry about as well.
It can be done, but don't assume "they will cash flow nicely". Occupancy rates are not 90%, it's seasonal, especially the mountains. I would run occupancy rates at 40-50% and see how the numbers look. Unless you're just going for long term tenants.
Also the value (in this case) is determined by the NOI, so assuming it will be worth 2x, is assuming your NOI is thru the roof (which is can be, but it's not likely in the first 5 years). I love cabins, and the RV park space, but like anything else, it's about NOI and there is a ton of blood, sweat, tears and busch light that goes into that number. It's not a get rich quick scheme, it's a lot of active work and I would have 5 yrs in my head at a minimum before you truly become established and stabilized.
Sticking things AirBnB does get you traffic, however it's not a 90% occupancy rate, again it's seasonal.
Hope this helps.