Found another moment to fiddle on my bike. Installed Honda Marine voltmeter where the headlight adjuster once was. Relocated adjuster knob just below original spot. Simple Farkle done by many. Used a dremel tool to cut the holes. Wired voltmeter to ignition and earthed via the green circuit. Used the tach light power lead to power the voltmeter light. Very happy with the setup. Incidentally, I took the opportunity to add my new dash shelf from Cal Sport Touring. Much better than the one I had made as it is far more rigid. Took a test run and got next to no vibration as opposed to my plastic model. I think a stabiliser bar would correct the vibration issue on my other shelf. Have a spare one now so can't complain...