O.K. that makes sense. I thought you were using a specific command so he would watch you, but if you are looking to mark any incompatible behaviour that works for you, then having the clicker is obviously necessary. I would be concerned that you could end up with a dog that only pays attention as long as you don't run out of treats…..a danger if you don't move to intermittent rewarding once a behaviour is on cue.
Leslie in CU mentions actually more frequent clicking as more beneficial for an overstimulated dog such a Dexter.
I'm thinking because the clicker is a secondary reinforcer it might be helpful…...provided he gives you something you can click!