Hi HB

Have a look at this https://www.demon-tweeks.com/uk/demon-tweeks-gps-digital-wireless-speedometer-dtmwds-02/ it could just be what you are after!

I have had one on my Roadster for the last year or so and it seems to work OK. I can see it in sunlight and the big plus point to me is there are no wires as such. A built in battery that only needs to be charged every 22 hours supplies the power.

It comes with various means of fixing but I just stuck a couple of magnets on the back so I can lift it on and off at will. You could also use velcro, sticky pads etc.

Interesting choice we both have in colours, I think mine is exactly the same as yours - Bentley something or other Burgundy.

Sir P