Kristy,
Fishing is only permitted now in the pond bounded by 600 loop, the movie amphitheater, the Bike Barn, and the Meadow Trading Post. A young child playing at the waterline was taken by an alligator years ago near the Grand Floridian and dragged under the water and died so Disney now has made most/all shoreline off-limits to sand castles and fishing and sun bathing (unless you are behind the rock/rope fence).
That means no fishing on the shore of Bay Lake (rope fence up with rocks close to shoreline) and not in the canal behind 300 loop.
There are plenty of "for fee" activities which Disney is only happy to take your money for.
Non-pay fun is following the old Fort Wilderness railroad ties behind 700 loop out to the emergence near the Settlement Bus Depot. Also the Tri-Circle D horse barn which is open 10a-3p to see the MK work horses (and other resort horses) in their stalls sleeping, eating, getting a bath, getting shoed by a farrier, or what have you (the pony rides take place here too). In the non-covid times there were organized games/activities in the field next to the Meadow Pool like volleyball, frisbee football, etc. The pool in the afternoons might be a good scene for the teens (hot tub, slide, back to hot tub, etc....). I doubt these are taking place in these covid times.
Also you may encounter some CM resistance (it's happened in the past) with the teardrop trailer being in a Tent/Popup site. Any rv/trailer is permitted one additional tent (by the rules that are rarely enforced). I hate to be the one to say so but better you hear it now rather than when you roll in. Tear drops don't technically qualify for those sites. The extra tent doesn't qualify you for the site category.
Teardrops qualify you for Full, Preferred, Premium, Premium Meadow. Then again, Disney may say nothing - they are VERY uneven when it comes to enforcing the rules. But at times they have asked people to move up to the Full+ sites when space became available during their stay.
Or else all the 45 foot rv's would be booking up the cheaper tent sites for all the holiday times and any other busy period like weekends in the spring/fall/winter. And then circling the campground looking for an empty all-hookup site to dump their tanks in every couple days (the Fort does NOT have a designated tank dump location).
Otherwise, have at it.
Bama Ed