Anyone tried installing the SON coax connector onto a B&M flat cable? Seems like it should be possible if the ends are stripped to the right length.
Other option is to run some coax cable and join it to the stock cable further up, probably directly soldered - putting spade or banana connectors on coax cable sounds even more bodgy than putting coax on flat.
Edit: found this guide to putting spade connectors on coax, doesn't look too hard actually. Plan B it is.