Go to Xshupa bay. Between Tulum and Playa. Take your wife or girlfriend as they have a great little outdoor restaurant. It will cost you about 5 bucks to get through the gate. Well worth it. One of the best spots I have kited.
Depends on the wind. East and Southeast work well, other directions not so. No car rental needed, taxi from town or collectivo, cheap and cheaper. If you've got a place on the beach even better. Do not leave anything unattended on the beach! Best to kite near one of the kite schools as they will let you leave your bag, pump etc at their kiosk, nice to buy the gang a cervesa for it. Pretty big shore break when winds are good. Big reef break, watch it over the reef as the water can be really shallow in the troughs, dangerously shallow. Stay clear of protected reef areas, best to talk to locals when you are there. Some really epic spots out in the Sian Ka'an Biosphere to the south towards Punta Allen, don't go without local though, there are several local kiters with vans that will take you out ask at the schools. Beautiful location have fun!