Some information for off-site rentals are:
Care Medical:
http://www.caremedicalequipment.com/
Walker Mobility:
1-888-726-6837
www.walkermobility.com
RANDY'S Mobility is in Kissimmee 407-892-4777
http://randysmobility.com/
Colonial Medical
http://www.colonialmed.com/about_cms.html
I have used Walker a few times. They will ask for a credit card and charge it the day before arrival. They will deliver the
ECV to your hotel bell services before your arrival and pick it up there after your departure. Their rates, especially for longer than a week, are much better than Disney's. Also, their scooters are much better. Also, they have different sizes and can handle up to about 400 pounds.
The only "problems" I am aware of with Randy's are that you must be present to take delivery of the ECV and also be present when it is picked back up. Also, they ask you to sign a waiver of liability. Everryone else drops off before your arrival and picks up after you leave.
You don't say if you are renting a car or what. If you are using a car for getting around, the
ECVs break down into five pieces, the heaviest about 39 pounds. They take about a minute or so to take apart and about two minutes (once you are used to it) to put it together.
Another suggestion is find out your state's requirements for a temporary disabled hang tag and get the paper work and have your doctor sign off on it. The tag will allow you to use any of the handicap parking areas (which will be a necessity). Also, with the policy of charging for valet parking, with a handicap hang tag the fees will be waived. Also the valets will usually volunteer to assist in loading/unloading an ECV. (I will normally tip the valets $5.00 if they assist in the breakdown and loading the trunk or unloading the trunck and putting the ECV back together instead of my normal $2.00 tip.) In Virginia I printed the required form from the DMV website. When I took the completed form to the DMV Office it took less than 15 minutes from the time I walked in until I had my tag.
If she is in a cast, you might want to have the person who puts it on you draw a line with a marker where it will be sawn off. Then bring a "Sharpie" type marker pen with you and have the Characters sign the cast. Warn them when signing to not cross the line. After the cast is removed you will have an interesting souvenir.
You can use a bungee cord to help keep crutches or a folded up walker on the ECV or wheelchair. Usually it would be a short walk with the crutches from the wheelchair or ECV to either an attraction to ride or a restaurant seat.
Good luck and let us know what finally happens.