I know this post will not exactly answer your question(s). But, I thought I'd share this for a bit of reference.
If I remember correctly, the WBXer Tranny Bell Housing is about 11mm deeper than the Diesel Bell Housing (the pilot shaft is longer). The DMF fits darn close to the engine block which makes the fingers on the pressure plate almost the same distance from the block as with the other flywheels depicted below.
The starter ring gear is the same on all three of the flywheels below.
In the pics below,
DMF on the left, G60 SMF in the center and an OE diesel flywheel that was bolted to a 1.6 VW Diesel engine on the right. They all fit inside the Diesel Bell Housing with some very minor clearance grinding for the DMF and G60. And, tabs on the G60 flywheel had to be knocked down (or at least I thought so). I did clearance grinding for the G60, thus, I did not have to do any additional grinding for the DMF to fit.
When I laid the OE Diesel Flywheel on top of the others to align the Teeth and identify the TDC mark, they were all the same diameter and matched perfect. Also, as mentioned above, the DMF (notice left side of each) is extremely close to the engine block when bolted up and the G60 is almost as close. Thus, the fingers on the pressure plate are almost the same distance from the block on all three set-ups. And, the starter will operate properly on all three flywheels.
Lastly, although not perfectly aligned in the photo below, if you notice, the TDC mark can be seen on the Diesel pressure plate to the right. Then, look at each of the other two flywheels to see where I scribed a TDC mark on them. (Remember, the viewing hole for TDC is not in the same location on a Vanagon Bell Housing as on the TDI transmission.
G60 SMF below
Diesel Bell Housing showing clearance grind marks..
In summary, I believe with the adapter and some clearance work on the WBXer tranny bell housing, a DMF should work just fine. However, the 11mm additional depth of the WBXer Bell Housing may be of concern. The adapter will add to that depth.
Let us know...
Hope this helps..