Hello Dirk,

First of all, I was never a student or assistant to Volker, and all my info regarding his attitude and convictions come from colleagues that did work or study with him. His legacy is manifold and IMHO had its ups and downs. I cherish some of his recordings, but they generally follow a desire to artificially build a theatre of sound, and in that respect he wasn't that different from others in his generation, like Günther Hermanns etc. One student of Volker later described his attitude as a man who wanted to be god, and I immediately understood what he meant. They were not interested in getting a transparent image of the performance, but they were aiming to recreate something more beautiful, more involving, more intense.
There's nothing wrong with that. Indeed it has sometimes succeeded in getting the musical message of a piece to the listener listener in a new and highly emotional way. These engineers were prepared to sacrifice "fidelity" to beauty, whereas nowadays more attention seems to go to transparency and an authentical representation of space.
For me, both approaches can succeed in capable hands, and none is wrong, or superior.

I hope my characterization makes sense to you, and maybe others who did work with him can chime in on how they would characterize his methods and ideals...

Would I be right thinking that the mics need to be packed vertical, not horizontal, to keep the more harmful horizontal smearing to the minimum? Stereo does not have much vertical information in it anyway.

That seems to be the better approach. The Rycote system for M/S is quite ideal for this.

Will I go to mic purgatory, if I just gaff tape them together with the diaphragms aligned?

Depends on whose mics you're taping...

Just get a hypocardioid and be done with it.

Have mics, will (ab)use... for fun and possible learning

I wish more of the 'budget' mic mfrs made a wide cardioid (hypo) capsule, however...that's what leads to all this madcapery in the first place !

I did, Gefell M950. The best.