I gave up on waiting for Mercedes and Ford to come out with the 4x4 chassis in North America. I have been looking for used 4x4 sprinter chassis in Europe. They can be bought for around 10.000. Compare this to a new chassis and you will have plenty of $ left to build a dream camperbox. I figured that by going this route (costs like shipping and import taxes included) you could have a very nice expo truck based on a Sprinter for below 50.000! All you need is the willingness to invest time and labour.
We can do a sprinter sized (flat packed, cold bridge free 2" walls, corner extrusions and adhesive) composite box including windows and door for around US$ 13.000. Turn around time is 6 weeks.