Just a thought - think i tried this a few years ago but cannot remember the outcome... what happens if you mirror the location of the agent files on the preferred server -
So set up a Ldlogon share on your pref server and only place the agent files in there?
This way you might trick the server - as it finds the exact path it would on the server to the agent files... I cannot remember if it worked for me or not and cannot test it here.
just a long shot!