Abby,
I've had a handicapped certificate (display) for years. I don't feel guilty about it at all. And the certificate can be used in any car you are in and whether you are driving or not.
In the hot months, MG gets exponentially worse while even walking short distances. I can get so short of breath. Same for the winter. And since we never know when our MG will tank, we can't exactly walk a long way to a store since we may not make it back to our cars!
These sites are only for examples of the foldable scooters they have now. I've considered this but don't really "need" one yet. Using a wheelchair might be too hard on the MG arms!

Glad you can do it, Alice.
http://www.scooterdirect.com/FoldableScooter~16.htm
http://www.planetmobilityscooters.com/
I have no idea if any of those have good reviews or not.
Each state is different when it comes to the reasons why you can get a handicapped certificate and/or license plate. I opted not to get the plate at this time either. I want to be seen as "normal" as much as possible.
Annie
They also make "seat belts" for wheelchairs too!!