I see we are writing at the same moment, talking past each other. One of the methods we did consider was using water and misting it off during the run, because the weight at starting would not have been measured weight.
Back in the day, as they say, we were particularly interested in leaving the line with a little more traction weight rearward while allowing the car to become more forward weight biased as it came to speed. Our cooling needs were different than yours, because we had an operating target of 145F for the stack but much less battery weight to carry. We had less heat to dissipate, but a narrower differential to sink it into (compared to ambient). That was the issue that forced early fuel cell cars into massive radiator capacity requirements.....not enough temp difference to radiate efficiently.
If you do dry ice, I would bulkhead the entire system behind the driver to prevent possible asphyxiation. Now that I know your voltage, I would be nervous about a water cooled, elecrolytic oil system. Those oils and greases need very little water to become conductive.
The possibility of vibration fracture, at speed on the salt, is NOT zero. On high pressure tires, in a rigidly caged and suspended vehicle, the amount of banging, shaking, and buzzing is a real eye opener your first time at speed. All of us have had stuff break, fall off, come loose, etc.
These considerations should be part of your "what if" discussions. In the end, your safety is in your own hands and high DC voltage in a salt environment is very, very serious.
