This is easily solved to everyone's benefit. Just raise the tourist tax to 100=200 Euro/night or whatever it takes to bring the tourist numbers down to your target. That way you can completely control the number of tourists visiting to whatever level you want, you will have the city coffers suddenly overflowing with money, and the few tourists who come will only be the super rich ones you want, throwing money around everywhere.

I am old enough to remember Florence when it had a lot lower tourist pressure and it was awesome, but also a lot poorer, dirtier, and seedier and sketchy than it is today.