Here's a thought:
My basic empty panel van is riding high (see the suspension/tyre survey), and driving it, it seems noticeably higher than other (loaded) vans, for obvious reasons...it's empty.
Therefore, logically VW do not consider the angle of drive shafts in this configuration to be of any concern.
So, if when converted/loaded, the height is made to remain as it is now, i.e. unloaded, then presumably they can't have an issue, can they, even if, to compensate for the weight of conversion/load, you raise it by the 25-50mm that it has sagged by....or am I missing something?