http://pdfserv.maxim-ic.com/en/an/AN723.pdf

A detailed tutorial about this very discussion. I wish I had googled "multidrop RS-232" before posing the question, but instead I had googled "multiple RS-232 devices on a single network", which got me nowhere.

So the end answer is that there are specific RS-232 Tranceivers designed just for the very purpose of developing a multi-drop RS-232 system (that remains within the EIA-232 standard)

The MAX3322E is one chip designed for this purpose. ($3 each)

Thanks for your input Bruce. I will now have to weigh all my options and perhaps order a dozen of these chips to build a prototype network.

-John