I love my 4x4 SMB. But note that what you CAN go over is not the same as what you SHOULD go over.
Every vehicle, especially a camping van, is a mess of compromises. It helps to be clear about what you wanna do.
And 4x4ing breaks stuff. A lot. Both outside and inside. It's just part of it. I did more risky stuff in my van earlier on, and then I kinda tired of fixing stuff. I was once more into the challenge of getting down tough roads and such, and vans are piss poor at that. They crown on stuff, have poor turning radiuses and sight lines, and the ride is horrific. But hey, you get your house way out there, even if interior screws and pots and pans are raining down on you. Especially horrid for passengers...yikes.
Another factor is that with a van you're often the biggest, heaviest thing around. Recovery stuff is really tough with a 4 ton van. I can pull out lotsa little 4x4 with my winch no problem, but they can't help me much. Sometimes just a little oomph will do it, but if you're beached, yikes.
So I got to the point where I towed a real 4x4, or put my dirt bike on a ca. Which is what you'd do for say the Rubicon.
I love the van. But I think if I were to do it over, I'd go with suspension upgrades short of full 4x4: like sways, lift, spring/coil work, wheels and tires, brakes, maybe gear ratio. Maybe even a locker. The greatest part of the 4x4 setup, though, was the transfer case. It really helps on descents esp to have that compound low with a heavy van. That would probably get you over the "white rum trail" (heh...Utah would never have a rum as opposed to rim trail, ya know?). And if I wanted to do hairier stuff, I'd buy a hardcore 4x4, side-by-side, etc.