Tammy Thompson and Paul Crowley were the first and best known exponents of using VIT for circle tow in the pre-bunting era. This makes towing much easier in very calm weather and allows the model to turn tighter on tow without dropping a wing and spiralling in.
I've seen these devices but don't recall them being published unless it was in the NFFS Digest. Paul Crowley called his a "kicker". It was a bent wire bellcrank that was free to rotate in a short length of brass tube which was glued to the boom in front of the glide stop. A line from the kicker was connected to the tow hook's latch so it would be released when the latch opened. When the latch opened at the start of the launch sequence the kicker's line was released, which let the d/t band pull the stab down onto its glide stop. The VIT angle was set by bending the wire and was fairly non-critical.
The sketch shown is mine, done from memory in 2006 and shows the stab in its towing position. I've omitted the d/t line for clarity. If you have a drawing or photo made at the time this device was current I'd be grateful for a copy.