I would try as hard as possible to get into Ft Wilderness for several reasons.
1. You will be entitled to use Disney transportation, which is a very BIG DEAL. We stayed there several years ago and we were able to ride the buses to the other resorts to use their pools, etc. At that time Ft Wilderness also had a big 24 hour pool which was great. The buses run till late at night and the bus stop was right near our site. Made it easy to get around.
2. Do not need to fight Orlando traffic every day and then pay for parking at Disney.
3. One good strategy is to visit the parks early and stay till part way through the afternoon, then go back to your camper, get recharged and take a nap, and THEN go back and spend the evening. Being able to use Disney transportation makes this a simple task - not so if you have to jump in your car and drive to an off-site CG.