There seems to be nothing to do beforehand in terms of aircraft fuel tax procedures and duty-free procedures for aircraft fuel in the case of aviation gasoline.
If you refuel the actual fuel, you will declare it by the end of the next month.
However, if you use various airports, you will have to prepare documents for each airport and declare it to each competent tax office, which makes the procedure very difficult.
Therefore, it seems that it will be easier later if you submit an application for approval in advance for tax payment area exception (see Q6).
Depending on the location, it seems that approval requires a period of nearly a month.