Maybe I'm missing something here.  Why would the mining rig (which isn't logged into very often) need to know how many bitcoins are in the wallet?  It just makes more.  It doesn't spend any.  Only the workstation where the spending occurs really needs to know how many bitcoins there are.  OH WAIT!  *facepalm*  I GET IT!  You're mining solo.  Otherwise, in a pool, this would make no sense.  In that case, automated transfers from the mining wallet to the spending wallet would publicly show a relationship between the two wallets, but it would be simple to set up.  As an aside, sshd is only a small inconvenience.