G'day Matt,
hmm - a dilemma to be sure - how about this:
Have a sub distribution board installed in one of the rooms - probably the control room - and ALL the power for both rooms is distributed from this board. That includes the 20A outlet for the Furman and whatever outlet is required for the UPS. That way the grounds are tied together at the sub board which is only gonna be a few feet from the outlets in question - you could even have those 2 outlets on the sub board itself - then we're only talking inches. The shorter the ground wires the less likely there'll be potential differences between them and thus less likelihood for noise to be introduced from that source.
Probably be cheaper than a large online UPS too.
As an aside, do you know if the US uses the MEN* system in power distribution the way we do here in Oz or does the way you use split phase distribution preclude it?
*MEN = Multiple Earthed Neutral
RE Catch 22. Never managed to finish reading the book - just got too stupid for me, though I did watch the movie - also too stupid
