gramps,
Interesting to hear Benchmark ran away from this. All I'll say about that...
Check Sprinter-Source for some recent feedback on Van Specialties.
Vanhaus does quality work but AFAIK they're buried with full van builds and not taking on any accessories.
Out and Upfitters is an offshoot of Mercedes Wilsonville (Swickard) so I surprised to see a Transit on their site, but they're worth looking into.
If MG at ExpoVans is preoccupied with other work, I'd suggest looking at Accessory Outfitters on the west side of Portland;
https://www.accessoryoutfitters.com
Better yet though, if you're willing to travel 3hrs SE to Bend Oregon, Jeremy and Max at J.ATT Industries (Google for contact info) could certainly help with this work for you.
HTH