Craft to customize Wheelchair

I don't know if this is the right place for this, but while I am rather crafty (I do 99% of our shirts for our trips), sometimes I have problems with the logistics of bigger projects and I'm looking for some help.

This October, we are taking my 87 year old grandmother to WDW and while she does not normally use a wheelchair, we will be renting one for her for our trip. I've been toying with an idea to, well, trick her ride. :-D I'm trying to think of a way to create a slip-cover style fabric covering to go over the back of her wheelchair that is "permanent" enough to last all week long, but will not damage the chair in any way.

What I'm thinking of is a piece of cloth that is the width of the chair back and twice the length (so it would form a loop around the back) and some sort of a closure at the bottom (either strong magnets sewn into a pouch or velcro strips across the seam). Then cloth would be decorated (perhaps with pins, patches, etc) to really add some fun. She's got a lot of personality, and I'd like for it to shine through!

Does that make sense? I'm open to feedback and other ideas!

It makes a lot of sense, but if you plan to put any bags on the back of the chair, it would not be seen as well. You could weave ribbon in the spokes of the wheels. For my sister's wheelchair that we used in a Christmas parade and nighttime festival, I used battery operated lights with garland.

I have thought about making something like the picture below and just using velcro or snaps to attach to the wheels and do vinyl iron on characters or phrases for my sister, maybe with a pocket or without.