From what I understand the best place to mount it is in the side case on the angled section facing forward and up. Use the Velcro to stick it on just like on a windshield. The plastic of the side case is easier to transmit through then a windshield. C14 riders who have done this report 100% success. Plus then it's protected from the elements and theft.
The new "Express Lanes" on I64 are now open. And from everything I read, motorcycles can use that lane *any time* for
free. I travel that road/direction for a good distance about once a week, so I decided it might be worth the hassle. It is only a single lane, so getting caught behind someone slow would be irritating. But otherwise, it is another option for travel if the main lanes had an accident. Or just because it is physically separated from other vehicles (wider lane and has physical barriers on about halfway) so it would increase motorcycle travel safety.
So I decided to plop down the $20 and the pass arrived today. I plan to mount it in the right pannier, exactly how you described. Nothing to steal, no number for someone to examine, protected from the elements, can't just fall off onto the road, etc. I am not sure how I will know if it is working or not, since they might use plate if the read fails and might not send any notice at all. Guess I wait and see. I am likely to use it Saturday night. So Big Brother will be watching....