maybe look at a civi version and put an ambulance body or Helmet top on it?
Humvees can be difficult to register and are missing a lot of the comforts/safety features we all take for granted...like ac, padded dash, 24v instead of 12v, cruising over 60 mph, etc... This truck has the old-school 8 bolt rims which are bias only...you'd need to upgrade to the 12 bolt rims. It had tie-rods on all four corners because it's independent suspension. It has portal axles which are great. And yes a stiff ride...but nothing compared to the offroad vehicles I've owned in the past. Humvees aren't great at anything, but they are good at everything.
As far as maintenance...sure, if you beat up a 10 year old truck in the middle of the desert, over-load it and drive it like a bat outta hell -- yes you will need a motor-pool to support you. I have good luck with my 97 (except the next point...
The down side of all humvees and civi hummers is the gm engine. Alot of parts available because they are everywhere, but over-all not the best engine, the td versions have had many problems over the years. AM-General went with the 6.2 and the 6.5 in the beginning because of it's relatively small size -- helps to retain ground clearance and not get too tall with the roof.