I know there is oversized parking. It used to be by M&F, but I believe it's been moved to somewhere in the Toy Story lot.
We stayed at Anaheim RV Resort. It's a very nice park with trees, some grass, and nice facilities. The ART shuttle stops at the office & there is a kiosk to buy passes. The route when we were there was first stop in the morning, and the first drop off home so it was nice that we always got a seat in the morning and didn't have to be on the shuttle long on the way home. It also only had IIRC 2 or 3 stops.
Uber can be cheaper than the shuttle if there are more than 2 of you. Uber is about $5.15 each way, whereas the shuttle charges between $4.00-5.00/day per person. It's defo cheaper than oversized parking, which I believe is $30.00.