So Garmin’s mounting system i.e.

Do they make a version which would just replace my headset cap?

Racewaredirect These chaps might be able to help – they do all sorts of custom Garmin Mounts, if they don’t list it just drop them an email.

I’ve seen them mounted back to front so it hovers over the stem, I found it mounted on a Odeg MTB stem is was at too much of an angle and prefered it on the bars (it’s fine on a negative stem).