Some rental companies have a clear pocket on the back side of the seat back that they will put a "name card" in.
Easy to pack, put on and take off: bright colorful bandanas or grosgrain ribbons. Tie them on to the handlebars, and your wheelchair will instantly stand out in a sea of similar rentals!

The only reason I wouldn't use tape is that the Florida sunshine and heat could leave you with a sticky mess that you will have to try and deal with under less than optimal conditions, and you don't want to have to pay a damage penalty to the rental company.
I know there was someone here last year who was considering sewing a nice seat cover that would go over the seat back, and down the seat.
If you don't have someone to push you, please be aware that if you have never self-propelled in a wheelchair before, you may find that you can't get very far before you find your arms have given out. If you are going to use the chair like a walker part of the time you may be able to get further along, but you may find that (especially) on the subsequent days, your arms feel like limp noodles, and your core will be screaming.
There are *lots* more hills, slopes, inclines and ramps at WDW than you realize, until you are on wheels.
If you don't have someone to help push, perhaps at least consider renting an
ECV? If you rent from an off-site vendor and have it delivered to your WDW resort hotel, the cost is significantly cheaper than the daily rental price at the Parks & Disney Springs.