If you are doing stall turns with a heli, you should have no trouble at all with a plane. Planes are generally easier to fly than helos. (I never got past a transitioning figure 8 with my old GMP Rebel years ago. Never even tried nose-in hover. One of these days I'll get another chopper. When I hit the lottery ).

50" wingspan on a .25 should be a fairly light wingloading so it should float right along. It is a tad big for a "park flyer" though.

A soccer field is doable, but awfuly tight once you are in the air, I suspect you'd wind up overflying the surroundings quite a bit, which if it's streets and houses would be a bad thing.

I really suggest you find an airplane club in your area to hook up with. Fly the cub a few times and see if you can keep it close at all times, as if you were over the soccer field. Better to find out in a safer envrionment. With an unfamiliar plane, it will be hard, and that plane is big enough to get quite far away and not seem like it. Once you've flown it a bit, you'll have better information to base a "soccer field decision" on.

My home field has a couple of roads near by, in a "no fly" area, but its amazing how many guys fly over it anyway because they don't realize how far out they are.

For flying in a soccer field, an electric park flyer would be a better bet.