We bought a screen door for a sliding glass door. It had a magnetic closure.
https://www.amazon.com/MAGZO-Magneti...eb_18326600011
We then cut it to fit the van doors and sewed 10 mm rare earth magnets around the perimeter I think they are spaced about every 2-3” across the top and 6-8” on the sides and bottoms. There is a ribbon that edges the screen and small pockets are sewn in to hold the magnets.
The magnetic enclosure works great and the perimeter magnets hold the screen in place without the mess of the adhesive Velcro on the van.
We used the extra screen from the bottom to make screen covers for the driver and passenger door windows.
It only cost about $40 per door.