Yup, that did it.
I went ahead and added a static route to both PFSense boxes, forcing their destination network through the appropriate GW. At least right now, My office can ping and hit endpoints on the clients side. I cannot yet ping my office from the clients side. That may be due to a pending reboot though.
For whatever reason, that seems redundant to me. But I guess you're saying that if the PFSense box is behind another router, then that sort of thing needs to happen? Otherwise if both boxes were up against the public IP/modem, that static routing would not need to occur?
Thanks again for a nudge in the right direction.
Now to clean up my mess, and work on DNS passing through.
-Chrisso