Saw a pickup some time ago where the person had painted on an epic scene of a wizard battling a dragon on their tailgate. Really well done, beautiful epic high fantasy chiaroscuro painting. I wish I could have taken a photo but...driving.
Put your disabled mother on the side of the van but with her face painted into famous scenes from the history of film. Your mom as Tony Montana wielding an assault rifle, your mom as the Big Lebowski holding a white russian, your mom as Linda Hamilton in Terminator 2 doing pull-ups, your mom as Robocop shooting off a guy's dick, your mom as Nosferatu emerging from the shadows, the possibilities are endless.
Some kind of innocuous but official sounding government agency.
Department of the Interior Development or something… liberally apply reflective striped tape in random spots, toss a yellow light-bar on top… you know, make it look official.
Now enjoy parking anywhere for extended periods of time.
Or just copy any of Krieger‘s vans from the show Archer. 
I’m going to switch my vote to the hybrid approach; paint the van to look like a bike lane, then you can park in any bike lane. Plus it’s just taping off two stripes and hitting it with a can of driveway crack filler.