Here is some of my hindsight perspective, FWIW. I took delivery of mine just under a year ago:
One thing I did not like about my 2013 Quigley conversion was that I had to get body work done to make room for 33" wheels. I also had to buy 33" wheels (rims plus tires). The thing looked frankly ridiculous the way it came from Quigley: their main customers are commercial not consumer enthusiasts with 'aesthetic' concerns, I gather. Ka-ching!
Another thing I didn't like is that you can't get a large gas tank. Range is limited and the gas gauge is not accurate. I may yet have a custom one built by that outfit in California or somewhere else - double ka-ching! The Ujoint tank will not fit my Quigley. In the long run I think I would have spent less going another route.
If I were to do it again I would probably buy the van on my own and send it to Quadvan or Ujoint to have the 4x4 conversion done with extra fuel capacity and the fenders/wheels/etc included.
That said, I am very happy with what we do have. We aren't rock crawlers, just snow and ice and muddy logging roads, that sort of thing. I have no experience doing what we didn't do, so I don't know what gripes I would have if we had gone one of those other routes. And at the end of the day we have a pretty unique vehicle that works just right for us.
2) Wilson RV cell phone booster. Better to have the cables run while the conversion is being done.
3) Custom Road Shower: viewtopic.php?f=16&t=11431
4) Cheap Penthouse air conditioner: viewtopic.php?f=16&t=14101
5) The fancy shunt-based battery monitor. I actually requested it with my rig, but it got dropped from the order somehow and although I bought it afterwards third-party I still haven't installed it. I know that by the time I get around to it I will have to replace my house batteries, because without a good monitor I'm just not maintaining them well. More ka-ching. (By the way, what the H*** is it with a modern RV electrical system that can't just bloody stay properly topped off by driving around with a high capacity alternator and a modern charging system? Seriously? It has to be plugged into the freaking wall regularly in order to not destroy the batteries?)
I bought a 48 inch Dometic Elite Oasis II door awning that I am going to try to mount on the roof rack, covering the rear doors. Enough times out in the rain loading and unloading, etc, plus the situation where you are parked with the rear doors open, and a rear awning seems to me like a no-brainer ... I don't know why there isn't a 'stock' one like the side awning, I definitely would have bought it. I can't recommend this project yet because I'm not far enough along, but I plan to post on it when I find one of those Round Tuits.
Folks have mentioned Five Star Tuning in other threads. I bought one in the hope of getting another mile per gallon or so out of my V10, which would pay for the gadget. I ran the van on the economy tune for several weeks and basically noticed no difference. YMMV (literally), and I wasn't after what some folks expect from their custom tunes -- just a bit better mileage on 87 octane gas. For me it was a bust, though it could still be a fantastic product for other uses.