Why should the racers (the best friend the salt flats have) be the ones to pay for the damage done by others?
There is long precedent for mining operations being obligated to mitigate the damage they do by extracting minerals. Unlike most mines the recreational use of the salt (racing) predates the opening of the mine. We have the historical senior interest in the salt and its welfare. Returning waste (for their purposes) NaCl salt to the flats should be a cost of doing business for them. We should not be obligated to pay for their damages.
They should be obligated to return by what ever means most effectively returns salt to the salt flats, more than they harvest.
Dry lay down is not a total fix but it would be a useful way to minimize damage to the lands end area of the salt. Sure it would be redistributed each spring but by not damaging the salt top crust in that area each year it would recover faster.
They could also investigate restoration areas which are flooded year around. I was up in Rocky Mountain National Park this last weekend and the National Park service periodically ropes off small areas around high traffic areas to keep people out so that area has a chance to naturally recover to a healthy ecosystem. The same technique could be used to improve the salt near lands end, temporarily dike off a small area immediately south of the lands end area from the lands end road to the highway and back a mile or two towards the bend. Run pumping 24x7x365 in that area including during the summer when evaporation would be highest, then once a couple million tons of salt is put down in that restoration area, open the dike on the east end of the restoration area and let that salt be carried out on to the thinnest area of the international course over the winter, it would build up the salt where it is needed most and increase the total lay down tonnage while still allowing normal recreational use of the historical race course areas.
Just like the National Park service does in mountain parks, help mother nature do her job without blocking normal recreational uses of the salt flats.
It would be a long term project, perhaps 5 - 10 years but it would substantially increase the amount of salt they could get across the highway each year.
Likewise during the normally flooded seasons they should be pumping at maximum capacity as soon as the last usage permit expires in the fall. The only way to get back to normal conditions for the salt is to move more salt than they strip for the mining operation over decade time spans.
It has taken 40-50 years to cause the current depletion of the salt it will take another few decades just to reverse the trend and decades beyond that to return the salt to the condition it was in the 1960's.
This is a long term problem with a long term solution. Don't push for a quick fix but push for a well thought out long term plan to get ahead of the depletion and accomplish effective restoration, not just a half Axxxd holding action at current sorry conditions.