I think I see what you are doing....
You might try looking at Supreme website
www.supremeind.com
Look at the Ford Spartan Body with a Bench seat option...
They can build that without exterior access doors (Strongbox)
The bench seat option gives you a 30" bench seat behind the driver
with you could extend or perhaps modify...
Check that out...
Also I work with Rockport bodys as well...
www.forestriverinc.com
They are in Elkhart and can custom build for you as well...
I like these guys a lot....
Unicell has a product that is unique in that it is a fiberglass..
one-piece design......The rigors of moving freight in/out of these bodies may not bode well for your needs.....just an opinion
...However they build a good unit.....
Get you specs together and send them to me...I will have these guys
build/price a unit for you....
P.S. - E-450 are GVW of 14,050
E-350 are GVW of 12,000
All 6.0 Diesels are in very, very short supply...in and you may be better off waiting for a 2005 unit.....
Send me an E-mail and I'll be happy to talk with you further..
Thanks,
Frank in Pa.
"The Beast in the East"