I intend to use a reduction drive, and definitively do like the added benefit of not having the crank take those loads. It is still attached to the front of the engine and imparting them on the case. I would love to mount the engine by the pulley end but there is just nothing there to mount to. I haven't seen a flywheel mount reduction drive for VW yet.
My first thought is a tensile rod on top and bottom squeezing the case lengthwise to offset the the thrust but I really don't see that working and if done wrong could be worse by compressing the case with easily 2-3 times the force that the thrust imparts.
There is also the possibility I'm overthinking this.
The average static thrust created is on the order of 4-5 pounds per hp so an 80hp engine might see 400 lbs at most- insignificant for almost any automotive case. There are enough direct drive engines flying to know that the prop thrust loads are generally no problem either since they are usually quite a bit lower than the clutch pressure plate force on a per hp basis. Gyroscopic and bending loads on the crank are usually much more of a concern and this is usually where we see front crank/ bearing failures rather than case failures.
The difference I see in a clutch is that the thrust load is applied close to the bellhousing and should not be going across the thinner sections where the cylinder bores are, depending on which is the thrust bearing. I could be wrong though, its been a while since I've had a VW engine apart.