I've never filtered, nor used fining agents in beer, other the irish moss during he boil.
I have had same issues of disturbed yeast in keg transported. What do now is a day before the event, pour off a couple glasses to get the loose yeast out of the current keg. Once pretty good, transferred the current keg to new one via each keg's beer-in connections, and venting off pressure on the new keg to enable transfer (old keg had about 5psi in the gas-in connection).
So now you have bright (clean) beer in the new keg with enough time to allow for replacing any carbonation lost. Since little yeast in bottom to disturb, no worries about shake up in transport.