Vincent,
That particular hatch door was a Sportsmobile design, unfortunately that hatch is not available anymore.
Does your van already have the hole cut at that location? If not, you may have other options:
https://www.etrailer.com/RV-Access-D...lo/SE38VR.html
https://www.etrailer.com/RV-Access-D...hoCNfQQAvD_BwE
https://www.speedwaymotors.com/Unive...hoCtK8QAvD_BwE
https://www.amazon.com/Leisure-Coach...20065ba91097f2
The measurements of the hatch door you have identified in the picture is 31" wide X 7.5" tall
I have not come across anything in this size - most of the longer ones that you find conducting s search prove to be twice as tall as the original, so maybe you place two smaller ones side be side??? Also, the original access door had a slight curve which matched the body curvature on the Van - not sure you'd find something similar - but someone with skills'' (as you) may be able to 'finesse' a metal hatch door to accomplish the same.
EDIT: You might also consider a Marine (boat) access hatch:
https://www.westmarine.com/tempress-...hoCDKYQAvD_BwE
You'll just have to search for a size that would work for you.
***Hopefully someone else on the Forum has knowledge of another option which would prove a better fit.