not opening ag pool this year. Tips/ideas to keep rain from collecting on cover

[AnnaK]

Since you're planning to drain the pool anyway, why even worry about a cover and all the resulting hassle? The walls will collapse without water but you could brace them with 2x4s. If the liner is removed you're not likely to have standing water and a mosquito breeding ground. Then you could build a railing between the deck and the pool to keep people from falling into the hole. It doesn't have to be fancy, it mostly has to be a visual deterrent.

[CarlD]

Some good ideas above.
But rather than a beach ball, which is far too small, you'll need cover pillows. These are about 10' long and 4' wide and inflate like giant beach balls, floating on the water and supporting the cover. My late dad used to get hold of used truck tire inner tubes and use about 8 of them tied together and tied to keep them in the center of the pool and cover because they were free and easy to get.