The choice is a RAM mount on the bars or make up something yourself,see 'quest on a Dakar 'thread.
I'm sure if you do a search for RAM mounts you'll come up with plenty of info.
Tony
I suggest you look at RAM-B-149Z (with 3" arm) or RAM-B-149ZA (with 1.75" arm), then RAM-HOL-GA15 cradle. It depends where you fit and the space available.
The U-bolt attaches to tubular bars of 3/4" to 1" dia. If 1/2" plus, then add RAP-319 shim.
To power the device look at QPAC (www.gpsw.co.uk) and there's 4 choices. The audio jack socket is either 2.5mm or 3.5mm option.