Wow, I need to check my comp for chatter, 3 posts back to back...
Unless your glove box door is lead or steel, you shouldn't worry about connectivity. Mine is "permanently" buried in center console.
What you should worry about, is alternator whine - there is no whine when BT runs off internal battery, but when you connect it to cigarette lighter power supply, or, in my case, hardwired to battery, there's alt whine. I have tried to eliminate it with a home made filter, but I need to recalculate the winds for inductor and the value for capacitor. Running BT strictly off battery is possible but not desirable. The whine is induced on the power lines, not on audio lines. A better quality power supply might rectify the issue.
I will try to attach a picture of the filter I made...
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