Like Jays I use a suction mount on my painted dash, it's from a Tom Tom though but similar idea. I was unsure of paint damage so I first applied a square of 'Defendall' the stuff that's used for paint chip protection. This way the protection is almost invisible and there is zero risk of paint damage, it can be removed in the same way as on bodywork, gently heat first with a hot air gun, I have the same stuff on my sills and change it every few years, no damage so far.