ProVan has a conversion built on the small chevy van 4.3 with optional AWD.
Search for them on the web.  Fine work.

Chateau has a conversion for a K5-GMC Blazer that is a walk through 4WD
Small camper on a *real* truck chassis.  Sadly out of print but occasionally
available.  A recent K5 6.5 Diesel with a Chateau conversion went for ~3K
USD.  Parts at your local GMC folks ostensibly forever.

Lofty Shelters markets a cartop camper.  Check "rolling estonians" on the
web for a few shots of it.

Met the esteemed estonians in Santa Fe over Christmas.  They have a fully
factory sponsored MB expedition going.

My answer is a 1989 Syncro Westfalia with the SA suspension, a magnificent
H-6 240HP broad torque curve Subaru with a 0.77 top for overdrive.

Cost of ownership to date available by private query.

p