I was encouraged by Spindatt's yoobtube channel on this concern: Note that he was using a QR block in a very high position (strapped to an ordinary rear rack) and, although he said the bike "wanted" to fall over in turns, it never fell and righted itself as it straightened out, post turn.

So, with apologies for the delay, I tested the towing part of my trailer rig and it was a resounding success. Trip was about a mile with normal bumps (road to driveway transitions) and regular intersection turns (as well as unintentional sharper turns when I geared too low and had to crab the bike to stay straight). Not once did the bike flop over. So I'm very happy