The bar I use is a 20mm GTD supplied bar with the ends cut off and an adjustable link fitted. You slide the fitting up or down the bar to soften or stiffen as required.
I use Dunlop Post Historic tyres which are next to useless in the wet, but I only have one set of rims so they have to do. A proper drift (when I get it right!) will allow me to carry more corner speed so exiting quicker than if all wheels are in perfect grip. Modern 17 inch tyres or slicks may not be the same in this regard.
The reason for the kitty litter experience was that I had chronic push as I turned in, went to "boot" the throttle to get the back round but because there had been zero change in direction as we were seriously aquaplaning, the car just went off that little bit quicker! All at well under 40mph at the Old Hairpin for those that know the circuit.
Ron was runnning his video in car so we do have video of 5 laps when I spun twice (Old Hairpin again!) and used the escape road (Melbourne Loop) once. Paul has said that if he can get copy he will post it on the GTD club website. There is also allegedly a moment when Ron was driving with me in the pits when he got his arms a bit twisted so I look forward to seeing that clip.
Charles was following me for a few seconds in his car and he runs 17 inch Goodyear F1 tyres. He just didn't have the same problems as his tyres can shift water very very well. Anyone planning 17 inch rims, these are the tyres for you for road and track day use.
I know what you mean about compression lock. I used to get it quite a lot whilst I learnt the car and played with pedal set up. I now have an adjustable throttle position and I have it so that when I am hard on the brakes with my foot straight across onto the throttle with the clutch depressed, the engine jumps to 4000 rpm (roughly). Took three days of mucking about to get this but it seems to seriously reduce instances of compression lock.
Visibility was terrible as you guessed. The cars in front were producing 15 ft rooster tails of spray! We played around with wiper position on the screen but even then the turn in for Redgate meant that you were looking through part of the screen that was never going to be covered by the wiper blades. Bring out the RainX!
Going back to tyres, looking at the cars in the background of your pictures indicates that you are also up against modern cars. Unless you run modern tyres of larger diameter you might as well go home. I run the 15 inch rims for period looks. The Dunlops I run are floppy sidewall cross plies. These are similar to the tyres that the cars at the Revival meeting run at Goodwood and the professional drivers there always seem to be in a slide in one direction or another. That is what makes driving the car more fun as an experience compared to up to date machinery. And more fun to watch cf F1! Charles and I took out the guys running a BMW 645 csi. They may have been minutes a lap quicker in the wet but we were having a lot more fun. In the dry my tyres kicked in and they were nowhere.