Using Air Tag (Bluetooth) seems like a bad solution.
Range is less than 10 m / 30 feet.
So you rely on your board being found?
If so, why not just write your phone nunber with a pen?
Apart from that, only 14 % use Apple devices here in Europe - so it has to be in US to work for sure, AND the board has to be found (stolen?).
If stolen, the device has to be so small it wont be removed.
RF has more range, but still limited and rely on a paired reciever same frequency.
Even planes black box'es beacon pings at 37.5 kHz only works under water.
GSM (2G/3G/4G/5G) seems like the way if you should be able to track your board?
So if a clever solution can be invented, great.

Peter