I didn't get the impression from the original post that Zoom planned on trying to run dodgy charters with an 'N'reg, more that he was considering buying something like a 172 to rent out to folks with American licences and was hoping to find out how much demand there would be.
The principal reason why someone would like to rent an 'N' reg aircraft is so that they could exercise the IR privileges of an FAA licence.
I know lots of people with an FAA IR, so I should imagine that the right 'N' reg aeroplane located in the right place, would be quite popular.