I have a couple tips, I have bad knees, hips.
Those gramma like hot water / ice packs are great for injuries. Think of hot water bottle holder over your head. Old pics come to mind.
These are great for ice. Better than ziplock bags because they don't leak. After several months they do start to leak, but run $8-$12.
If you bring one along. You can stop at where they sell pop (indoor places) and get a cup of ice and fill the ice bag. You can do that with a ziplock bag too.
You can also get ice packs from first aid stations.
I find its best to ice first thing in the morning to combat swelling, and when you get back to the room at night.
Icing first thing helps, last trip forgot one morning (or lazy) had to do the stop at first aid as me knees really were in pain by mid afternoon.
If your able to take ibuprofin, motrin, or if you get rx celebrex or the like nsaid, don't forget to pack some with you for in the park.
I've sat in lots of wheel chair sections, and nothing worse than hearing from the lady next to you rubbing her knee, she left her meds in the room. You feel their pain.
I wouldn't bring the whole bottle into the park, in case you lost it, but enough for a day or 2, if you use it, refill it back at the room at night.
Offsite rental will most likely be the best idea. Not that important maybe first thing in the morning, but afternoon, or evening trips back to the resort, that one long walk to the busses, and busses to resort room.
If your able to walk a little bit. I wouldn't recommend sitting in the wheel chair the whole time. If you able to get up for short periods and walk, thats great for your legs. You don't want to loose tons of muscle mass by deliberately being seated because you have a chair/
scooter, and feel like people are thinking your are "cheating the system" by getting a chair. Your preserving muscle mass, and you of course don't want to be sedintary if your not required to completly.
All depends on the injury, if the doc says stay off because its broke, by all means listen. I'm just mentioning take a 10 minute walk, 20-30 walk if you can handle it, and it doesn't hurt your injury.
I take breaks out of the scooter. My husband has no problem riding in the scooter, when i want and need to stretch my legs. I definitely can't be walking 10 hours a day, yikes, even 5 hours... I'm already in pain every day, I can't imagine what that would do to me.
People may look at you funny like your cheating, but I can guarentee you no-one wants to switch places with you and be in pain.
But, from experience, being in pain every night because I was too stubborn to try out the scooter/wheel chair was a big mistake in my mind. Trips are more enjoyable since I'm not in constant massive pain from being on my feet.
Have a great trip.
Don't forget being in the water feels great on an injured joint.
Connie