Situations like this when a race is postponed and run the following day, they should have a half hour practice period in the morning. IndyCar has a warmup on the morning of race day to allow any changes to the cars for track conditions that day.
Also I think that the rule should be amended that work can be performed on cars during a red flag. Formula One allows the cars to be worked on when the cars are on the grid during a red flag. Assuming it is safe to do so, the cars should be led onto pit lane when a red flag is thrown and parked in their pit stalls. If a car has to go to the garage for deeper work, then they will have to wait until a yellow flag is thrown to work on the cars. You can do a lot to fix a car in a pit stall.
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Opinions expressed are my own.