ISTR an openwrt (or dd-wrt) package that included catch and release and a number of figures that may or may not offer a full and cheap solution to this. (wifidog?)
How the owner expects to manage that data is an interesting use case, but it's a cheap option as the firmware will run on a whole bunch of low cost routers.
50 rooms is not a small establishment, and actually quite surprised it doesn't offer wifi already, possibly sweet-talked by Spectrum for silly money.
