if you have the JBL system you probably also have 3-zone digital AC. i know the climate/temp sensor for the driver side is straight in front of your right knee - it's a set of small slots below the ignition. not sure where the sensor is for the passenger (it might be in the blower, behind the glovebox), but i can't imagine that it would be up on the top of the dash, since the sun would give false temperature readings. and i wouldn't think a dash cover would go so far down as to cover the temp sensor on the driver side.
even without the JBL system, the center grille (which doesn't have a speaker in a non-jbl setup) still gives some reflections in the windshield, as do the wood trim pieces on either side of the radio/ac stack. ask for a picture of the actual cover to make sure it covers the grille before you buy.
worst case you can probably remove the JBL logo. the grille simply snaps in. wedge a flat plastic pry tool in between the front edge (closest to windshield) right in the center, and pry the grille up. be careful, as the speaker is attached to the grille and has a short wire. thankfully the wire easily unclips so you can work with the grille outside the car if you need.