A lot of good hints - although since the original post was from September, the poster has probably come and gone already. But, since there is so much good info here, it’s still worth responding to.
I also have a daughter with CP. She has mixed type, but is predominantly spastic quad. She can only stand with support and needs to be lifted onto rides that she can’t stay in her wheelchair for.
We have tried an umbrella to shade her when she was small, but we personally found it to be more trouble than it was worth. The reasons we didn’t like it was that it was kind of in the pusher’s way, prevented us from seeing her and got it the way for transfer and the bus and we needed to put it down during shows to not block others’ view.
We so found it didn’t help as much as we thought it would since much of the time it didn’t actually shade much of her body - if you’ve got one you could adjust the angle to keep up with the sun, it might be more helpful. We just have a hat with a big brim on the front and find that works better for her.
Remember sunscreen for the knees and exposed parts of legs. One time we forgot about that and she ended up with burnt knees - in a wheelchair, parts of the body that would not usually be totally exposed to the sun are pointed right at it.
Water rides are great, but you might get soaked to the skin (especially Kali River Rapids) and you may need to change to dry clothing with no good place to do it. And, putting a wet person into a dry wheelchair makes the wheelchair wet. We also find Kali challenging because everything is wet and slippery.
Because we need to lift our daughter in and out of rides that are not wheelchair accessible, we try to alternate things that are completely accessible with those where we will have to transfer her. We also try to be aware of lternating long rides like Haunted Mansion with shorter ones where you barely get settled and the ride is over and you need to transfer out again.
F posters have not seen the disABILITIES FAQs thread, it’s full of collected information. You can find it near the top of this board or linked in my signature.