Wow, that thing rocks!
In the 4x4 Community a Unimog is the guy that can carry a dozen donuts, and two cups of coffe at a nudist colony. (think about it)
The only place I can think of is
http://www.pirate4x4.com/forum/ they have a 'Mog section, but not much info on what you want to do.
If you search around that site, you'll get some different ideas though. Be warned though, those guys and gals don't play nice, and won't tolerate any kind of attitude. They are HARDCORE. Don't expect a hug, and remeber that if you get flipped off, it's a friendly way to say Hi over there. But, it is THE place for info for 4x4's.
A crane would be cool. If you had a rear winch, you make it do double duty with a few pulleys. Or, you could put a hydraulic pump on that rear PTO and use a hydraulic ram. Heck, you could even make a log splitter for camping with that setup. No chopping firewood at the campsite!
What kind of auxiliary lighting? It should have enough alternator to run as many lights as you would like, so that shouldn't be a problem.
With a flat bed, you could have tabs to tie a tent down.
As far as a air hose reel, just use one of the ones from just about any store. Does it have a tank? or just a compressor. If you run any kind of air tools, you need a tank. Most just use an air brake tank from a semi truck. Common mod in the offroad community.
Fresh water tanks? Look at some RV's they use them in just about any shape, and size.
As far as recovery, read this:
http://www.pirate4x4.com/tech/billavista/Recovery/ . Most people with a winch have no idea how to use it properly. With the size of your machine, you are getting into some serious loading on a wire rope, and I would hate to see someone get hurt or worse.
Pirate should be able to point you in the right direction for fuel storage.
There are so many attachments for a PTO that it's rediculous. Generators, winches, pumps, etc.
Another thing to think about on a rig that size is a rear winch. If you plan to go offroad at all, sometimes it's easier (and smarter) to go backwards to get out. If you manage to get a Mog stuck, and you can't unstick it, it's one heck of a tow bill (if they can even get to you).
If you fabbed up that bed, you should be able to fab up most of this stuff with a few ideas.
Good luck with it, and keep us posted on the progress.