Here's my current solution. B&M's biggest cooler on the left, another one for engine oil on the right, and you can see the Derale power steering cooler on the far right:
This is what temperatures looked like at LVMS last weekend:
Now, the transmission loop in the radiator is still hooked up. What happened was the transmission temps were stable for two laps until the water got above 200, then the transmission started climbing rapidly, trying to reach equilibrium with the water. It climbed much less rapidly than the last time, since I've removed the engine oil load from the radiator. Which is good. The oil cooler was a good idea.
My next move is to disconnect the transmission loop in the radiator and get all three systems independent of each other.
The other concern is the water temp. Why is it climbing so much? This course was completely flat, so I'm not working the torque converter much. There's only two high speed sections, but digging into the data, the temps climbed during everything. The trans temp would rise while I had my foot in it, then start falling off as soon as I started braking and turning (the bumps in the green line). That's what I want to see.
The engine oil stabilized at 240 late in the session, which is perfect.
But the water temp just kept climbing. The radiator couldn't shed the heat, and I've got the big one GNS sells with the dual 1300cfm spahl fans.
The answer is airflow. The engine bay is getting pressurized and enough air isn't flowing through the radiator core. I can see it on the highway. In traffic, the car runs right at 160 all day long. Once I get on the highway rolling 70, the temperature climbs to 180. I'm non-lockup, but at 70 on the highway, I only have 1-2% converter slip and the transmission is running at 140.
The only explanation is lack of airflow through the radiator at speed. GM figured this out back in 1986. It's why McLaren put the fender vents on the GNX. Removing the weather strip at the base of the windshield helps below ~40mph, so keep that in mind if you're out somewhere and need to limp it home. Above ~40, a high pressure zone forms at the bottom of the windshield and starts packing air into the engine from the top, so don't remove the weather strip if you're going to be on the highway.
I'm getting a vented fiberglass hood over the winter. The ground wire for my fans also showed some heat damage, indicating the fans are sinking a LOT of current, which means they might be on the outs. My hope is a vented hood and replacing these fans with newer units should finally solve my three year battle with heat in a track application.
As for the dipstick. Get rid of the stocker. Lokar sells a locking dipstick. I use that, plus I attached an overflow can to the vent. If you overheat it and the fluid boils, it's going to come out the vent until you overpower that, then the front pump seal or the tailshaft seals will fail. Which are bad, but you won't have a fine mist bursting from the dipstick tube at the top of the motor and catching fire on the manifolds, which actually happened to me. You'll get a prodigious leak that'll come out in spots far enough away from the exhaust to not catch fire.
My case is extreme. I'm flogging the car hard for 15-20 minutes at a time. Not ten seconds. A drag and street car should not be having heat issues unless something's wrong, even with good condition stock equipment.