Rainbow Mages and Searching in the Early Game

[thejeff]

In general, be done with it by the time it's likely to be an issue. Script to retreat (Or a couple spells to help the local PD, then retreat) in case of attack events.

If you've got a neighbor you don't trust - no communication/no peace deal - who you think would be able to target him, get him back to the capital.
If you're not being rushed you should have a year or so before it gets too risky. Remember it'll take time for your enemies to get enough scouts into your territory to reliably locate him. Then they need to have assassins or spells ready. And be ready to start a war to take advantage of his vulnerability.
After the first year or so, it depends on your relations with your neighbors. You may be able to risk site-searching with him or you may want to use the remote spells or other mages. By then, he's likely to have forging/casting to do much of the time anyway.