RE: Cab over Camper shell?
Google the term "mobile treatment center". You will find several manufacturers of fibreglass shells which could easily suit your purpose.
RE: HWH customer service phone number is a joke
I have had dealings with HWH twice. Once indirectly through Triple E when a hydraulic hose developed a leak - they sent a replacement quickly and charged almost nothing. The second time was when I ordered a set of jack springs. They arrived promptly and reasonably priced. They were most helpful on the phone when I ordered the springs. They are fantastic to deal with.
RE: Freightliner Odometer
Some Freightliner odo's will indicate both miles and kilometers. You press and hold the trip reset switch when it is in total distance mode. A reading of 100K miles would switch to a reading of 160K kilometers.