We have received 3 separate reports this week from Yachts who have been using jetskis to tow guests on inflatable toys who have been stopped by Guardia and either fined or given a warning... not because the crew member riding the PWC/jetski didn't have a RYA PWC licence but because of the nature of the activity. Rules in certain areas around the Med, and particularly in the South of France state that the 'towing craft' must have the capacity to carry ALL persons, i.e. those on the inflatable in addition to the helm and observer on the towing craft.
Therefore, if you're towing from a 3-seater jetski, once you have a helm and observer, only one person can be on the inflatable toy..
Stay ontop of the local regulations to stay out of trouble..