Why don't you just leave your purse at home?
When we fly to Disney World, I carry on my roller bag and then whatever bag I'm going to carry in the parks with whatever I intend to carry in the parks. I leave my regular purse and stacks of random credit cards and keys and whatever else at home. So when we get to the resort, I just give them my roller bag and me and my park stuff head out.

I usually just carry a small wristlet kinda thing at the park, if anything, so I have that with my ID, credit card, passes, and cell phone.