Syncing RADIUS between sites?

So my friends and I have started fooling around with site to site VPN over pfsense, mostly to make LAN gaming a little easier. We also mess with networking a bit, and we periodically find ourselves digging through each others router configs. I know pfSense can authenticate via RADIUS, but is there a way to sync a freeRADIUS server between me and my friends house? We have done this with BIND DNS, I'm the master he's the slave, but the only similar option I saw in FreeRADIUS was SQL sync and if there's a better way I'd rather not set up another SQL server if I didn't need to.

We want to use RADIUS instead of just manually updating our pfsense account because it will also allow us to sync credentials from the remote access VPN we have, plus the wireless APs at our various houses could use WPA2-Enterprise with RADIUS.