If your panniers are fiberglass or mystery plastic you can stash the ez-pass in there...it should work fine. I have mine in a windshield bag. But I lock it in a pannier when i feel the need. But the reason the EZ Pass people want bikes to go through a tended booth, is that there is no specified location for tags on motorcycles that is guaranteed to work. They say put it where ever is secure for you, and go through a tended booth. If it does work you will get a green light. If not, you can pull it out and wave it, or tell the toll taker to take your picture...the toll will come out of your account eventually, so long as your EZ pass tag is associated with your bike's license plate.