Many manual transmissions are built in such a way that the rear bearing, center main shaft bearings, and output seal will get no lubrication if the input shaft is not turning. When being towed, only the output shaft is turning.
Damage may occur due to lack of lubrication. It may take a while, but eventually the bearings and seal will be damaged.
I don't know if the Mazda 5 speed manual transmission will lubricate itself when being towed or not.
Some people have stated that they have towed their Miatas many miles.
How lucky do you feel?