I've had a 4x4 Ford E350 Camper Van (Sportsmobile) and am currently running a RAM 3500 with XPCamper. I view both as a very different vehicle than the 200 Series, an addition to the fleet, never a substitute. Neither really could be daily driven.
I don't fit in the smaller vans, (shorter beds, not enough head room) so I'm stuck going a bit bigger with the base vehicle than some can get away with.
Once you go camper, you really end up with a bunch of complex tradeoffs that don't have right answers. Every one ends up somewhere different based on their priorities. An expedition camper ends up being a kitchen, bedroom, living room, power plant, sanitation system and off-road vehicle. Weight goes up very fast and ends up being the driver for most decisions. Correcting "mistakes" is a lot more expensive than say picking out a new camping stove or folding camp chair.
I guess there is a space for comparison of a lightly optioned 4x4 sprinter, with minimal built in camping amenities, for which the additional weight wouldnt compromise it on/off road much more than a 200 Series. But I'm not sure it would be that much more comfortable/convenient then a well thought out tent based camp carried in the back of a 200 Series. Beds take up a bunch of space. I found in the camper van they would have to do double duty with gear. So the idea of just parking and sleeping never happened in practice. It was park, pop the top, shuffle the gear to get into a configuration where the bed could be folded down and made up for sleep. Then everything re-shuffled to get in a kitchen configuration in the morning. In the XPCamper that has more room, we still end up setting up an outside kitchen in everything but rain and cold. We like to be outside, and given the space constraints of the camper when occupied by 2 people + dog it just ends up easier. All in all easier than a tent and ultimately more comfortable, but still some time is involved.
One thing I do notice is that while the Sprinters have decent enough power, cargo, and tow ratings, I do end up passing the Sprinter Camper conversions a lot, particularly on steep grades. They don't have 200 Series v8 power let alone a domestic full size diesel.
Anyway, expedition campers are awesome, but many more tradeoffs than a expedition SUV have to taken into consideration when building one up. Go slow, get on a Sprinter forum and see what tradeoffs others have made, poke your head into them when you seem them out camping. Visit a couple conversion manufactures to get a sense of the range of possibilities.