I looked at your picture.

That looks like a 12'x30" inch Intex, which holds ~1,500 gallons. Did you realize that weighs more than 6 tons -- 12,000 lbs?

I'm pretty sure your platform wasn't 'engineered' for that, and if you tried to 'level' it, the platform would just break.

Here the options I can think of:
+ Leave it as is. If it works, it works. If it 'tips', you're no worse off than you are if you drained it.

+ When you drain it -- or it 'tips':
+ take the plywood off,
+ put SAND under the pool, and level it.
+ add framing to contain the sand in place
+ cut the plywood to fit around the pool.
(Use Gorilla tape on the plywood edges next to the pool!)
I don't think you really want to get into framing a platform that will actually SUPPORT a 6 ton pool! This way, when your done with the pool, you can take up the platform and just rake the sand out into the grass.