I'm working with a similar problem (10 on-site workstations and 3 new remote users). Have you considered dial-up networking?
I've been kicking around the idea of
a) remote w/ synch - very complex to develop, I've looked at sychdek but have thrown that out the window due to it's limitation with repeating fields.
: laplink or other forms of remote access software - not good since printing is required by remote users.
so that's left me with
c) dial-up networking - not too difficult, I'm just not sure what sort of overall I/O I'd be dealing with from FMP.
I'll keep you posted.
-Brian