An aluminum service body (kept within truck body lines so as not to adversely affect aerodynamics; nay, improve them some) would be one of those Won the Lotto projects. They are quite expensive, overall.
The budget should start at around $6k and go north of $30k for all out custom.
I don't know what difference would be made for accident avoidance. They're also expensive to fix. But being able to integrate space for tools, supplies, generator, extra fuel, etc, would be great.
Sorry for the frustration.
1990 35' Silver Streak Sterling
; 9k GVWR.
2004 DODGE Cummins 305/555; 6-manual; 9k GVWR.
Hensley Arrow. 10-cpm solo, 18-cpm towing
Sold: Silver Streak Model 3411