Yes, possible. Simplest possible way is via linux containers which would require no server changes at all. And strongly suggest those customers to just go this way.
If that's not good enough (why would it?), then we need:
a) ability to install server to different places (we already provide some "relocation script" for at least customer A)
b) configure different server instances to use different ports and different erlang node names. That's appears to be not hard to do. Perhaps 2-3 days.
Maintenance cost of this feature can be large. I.e. we do maintain cluster_run, but at various points in time we had varying limitations. Like not being able to join "normal" nodes to cluster_run clusters and stuff like that.