Keep in mind in the passenger compartment, you can smell the electrolite from the batteries on a long trip, this is vapor from acid not something you want anyone exposed to for long term........
I worked on the Iltis since they were brand new, and I can tell you this: 99% of the time, if you can smell the batteries, it is overcharging. And if it is overcharging, there is a reason. Again, 99% of the time, it was due to loose battery cables or terminals. And by the time the operators would report it, or more likely have the vehicle die at the side of the road, it was too late. Both the batteries and the alternator would have to be changed.
Although in part a design problem, by putting the batteries so deep into the vehicle, it ultimately was an operator problem, as they were responsible for the servicing of the battery compartment, and a daily inspection which included security of the cables and terminals.
Other components which typically gave problems with the Iltis included the ignition system control module (worth around $600), the upper balljoints, the speedometer (good luck finding one of those), CV boots, and the electric fuel pumps. Also, anything 24Volt was worth a fortune. The signal flasher was around $500.
I personally wouldn't own one, but if I did, I would convert it to 12Volt. I would also try and mount the battery under the hood vice under the rear seat.
Cross country, they were geared too low compared to the old M38A1s. Made them lousy for hill climbing, but then again they could go 70 on the highway, unlike the old Jeeps top speed of 55.
My biggest heartache with the Iltis was all the nylon and plastic clips and bushings located all over the vehicle. Army trucks are supposed to be rugged and simple, and not have a hundred different pieces which would break, fall off, and just plain wear out.