One quick note about hanging rucks on the trucks. I was with the 82nd in Fallujah, nad when we ran missions from our FOB (foward operating base), the only things we had were ammo, 1 case MREs, ammo, 2 cases of water or 2 cans, ammo, medical kit, ammo, and usually an assault pack per man. If we were relocating to another area, 1 ruck per crew member, 1 cot per crew member, one duffel bag per, all the water and food we could find, and of course ammo.
I'm not sure what kind of dio you are going for, but the Marines that relieved us had 5 man crews in their HMMWV gun trucks: driver, truck commander, rifleman in one of the back seats, gunner up top, and an additional rifleman to watch the gunners back; he rode up top with the gunner seate4d behind him.