Some of these vehicles had all sorts of things tied to the sides, or carried in all sorts of ways. The German army was partly motorised and there were also many horsedrawn units. Many of the field kitchens were equipped with a variety of vehicles, and an armoured unit kitchen maybe appropriate...
Once war gets underway soldiers find a way to tie as much of their gear as possible to a support vehicle rather than have to carry it, and would hang out the sides of vehicles when the oportunity presented itself to save your legs 'cause you had already marched, ran, walked, dragged yourself many miles over the last three weeks.
Have a look at some of the bits that are available for building diaramas and picture yourself jamming as many "grunts" in a vehicle as university students manage to....
Packs and webbing equipment tends to vary between people and areas, for example, many people would carry extra water in hot climates, or extra clothing in cold areas. Uniforms varied as units were resupplied replacement personnel.
Hope this helps, Peter