You have two internet connections, two MTs and two networks, and two hotspot pages. you are saying you can’t control what hotspot page the user gets, well thats really determined by what SSID they connect too. Other than that, its simple. You can do that all with ONE MT if you wish, but again, depending on the SSID that you select it will determine what hotspot page they get and what internet they use.
How do you want to determine what customer gets where? If it is two buildings right next to each other or two businesses, then the only thing you can do is put in more APs, but turn down the power so that they only work inside that building.