Many things I've read over the last couple of weeks on the proper
grounding of towers and ham stations all emphasize the importance of a
single point ground.

What if it's not possible to implement that?

My tower is on the other end of the house from where the electrical
service (and its associated ground) are. I did not put the tower there
and if it had been left up to me it wouldn't have gone there, but that's
another story for another time... point is that the tower and the service
ground are 50+ feet apart, and the shack (using the only available spare
bedroom) is on the end of the house where the service ground is.

I can beat a fistful of ground rods around the tower, and put another one
in the ground below the shack window (that's the one I'm doing now), and
bond it all together with buried heavy gauge copper wire that also bonds
to the service ground... but that ain't a single point ground, it's more
like a 50+ foot long distributed ground.

So, how do I achieve that ideal "single point ground" in a situation like
this?