This post has been turned into a bash fest. He is asking for help to design equipment that is good.
Unless you want to help him with the grant paperwork or have your department donate a truck to his department please stop it your point has been made.
One of you stated that your department turned in a substandard truck that eventually killed some one. Your department was neglegent for turning in this unit. It should have been scrapped due to the fact that you knew about the flaws.
Another example was putting a 1000 gal tank on a duece and it would get stuck on soft ground. the truck is rated for 2 1/2 tons off road and 1000 gal of water weighs about 4 tons plus the tank and other equipment. The truck was overloaded for off road.
A department that spends all of its money on new equipment but does not have any money left for training may look great on paper but in reality is less effective than a department that has good equipment nad actually trains.
No one has talked about the DOT regulations that affect the trucks and the state laws that cover the drivers.
If the trucks are designed to comply with the DOT regulations and the drivers meet the requirements of the state for the class of vehicule they are driving than the liability issue is muted.
Now back to the original question
Please look through this site. They have a lot of information that can be downloaded on this subject.
Roscommon Equipment Center
WS Darley can supply anything from parts to slidein to complete trucks.
Complete Source for Firefighting Equipment Including Turnout Gear, Rescue Tools, Hazmat, Hose and More - eDarley.com
You mentioned the Duece and the Hmmwv but you did not mention the Cucv and the Cucv2
The duece is a truck and should include specific driver training unless the driver has a CDL with the tenk endorsement.
The Hmmwv is wider that the Cucv and should be be driven by drivers that are aware of this. this width can be a hinderence in tight situations.
The Cucv and Cucv2 are pickup trucks and can be ourfitted with slid in units.
The capicty of the duece is a bout 500 gallons and the smaller trucks is a bout 200 gallons.
Remember
Driver training is very important
Keep the CG low
Build it well
Another option that has not been mentioned is does your city have access to DRMO equiment? They some times have AWD fire trucks.
Good luck on your effort to help your department.