I'm imagining that the trying to keep the back under the person would be a problem. I've not really known many folks in wheelchairs but observing the transition process from one place to the chair or from the chair to another place can be a fairly awkward and cumbersome process without having to worry about making sure the skirt doesn't fly up or the back get out from under them. Maybe it would be one of those things that when you get the process right it's no issue.

As an alternative, maybe something like a skort that could be buttoned and unbuttoned ie. the UK modesty system. No pleats but a full apron on the front.