Hiya,
Well done selling the whole camper idea; although that bit could be the easiest. She looks at Unicats while you keep quiet, then says it would be nice to have a camper that goes anywhere...
Why on earth did you buy a DoKa when you didn't need one? The'yre so rare that they command higher prices than their single cabin equivalents.
I'm with everyone else on this one. For having given up on finding a DoKa in the size and power category I resolved to make one. I wouldn't do it again unless you paid good money. I promise you that you have so many other things to sort out on a camper that you don't want to add car bodywork complications to your woes. Don't cut it; there'll be wiring, cab mounts to move, ill-fitting parts, stuff to suspend in place while you tack it together. And at the end of the day you will have a cut and shut whose welds you won't have treated inside.
Cos pressed steel bodywork has cavities that you can't get a brush to, and spraying blindly is not ideal.
You could keep the Doka and cut out the whole back to include it into your living space; the rear seats pivot to form part of the lounge, or actually have the lounge in the cab, then you can shut it off as a spare room. I don't know whether you have kids that have flown, or are the before kids stage. Either way something will crop up to make you glad to have four or more seats.
With the DoKa demand it's a shame to cut it up.
Rather than start hacking apart the cab, get the body off, give it a general clean up. A load of T-cut on the body and steam wash the chassis and interior.
Once the body's off people can see the potential more easily, at that point resell it at a profit and get a single cab or a MAN 8.150.
There are lots of young adventurous families out there who baulk at the work required to strip an existing body off and want to be able to start the build directly on a nice clean base.
As already mentioned, don't think of it as your only build. Get this one rolling, learn from your mistakes and build a better one later.