Best Place for Aftermarket Bluetooth adapter in 1996 Z3?

Hi, It's been a long time since I've been on the BMWCCA website.

I have a 1996 Z3 which I bought new, it was supposed to leave Greenville the day hurricane Fran hit in September 1996.

I recently finally updated the radio. I bought a JVC KDX50BT from Crutchfield's which I'm quite pleased with. However, I took it out and re-installed it about a week ago to improve the installation of the hands-free microphone, and now the bluetooth sometimes cuts in and out.

The bluetooth adapter is a little USB dongle which plugs into either the front USB connector, which I'd rather leave available, or to the end of a longish USB cable coming out of the back of the radio. I suspect that when I reinstalled it it ended up somewhere under the dash surrounded by more sheet metal which is causing the problem.

So before I pull it out and move the adapter, if anyone had advice on the best place to try to put it.