It seems like it should work. Where it gets a bit tricky is that it used to be we offered the two models of "Core" and "Interactor". The "Core" based license meaning that you purchased a certain number of cores, let's say 16cores as an example. Then you could either do a standup of Tableau Server with a single standalone box of 16cores or you could have two boxes each with 8cores. But with Core you can have as many users that the system can handle within reason. The "Interactor" is more user based and we don't really look at the underlying hardware (except to verify it meets *minimum* standards). So if you had a 100 seat Interactor license, you could have a mult-node system and continue to add nodes as long as the number of licensed users on the system does not exceed 100.
In a nutshell, I'd be really surprised if we tried to limit you by sites. That is, we've never really done that in the past.
Yes you can, we have done like that