OK and thanks for all the input (those who did) so we have a go and here it is:

10 - Win
7 - Place
5 - Show
4 - Super

If the winner really excels then he or she will get extra bonus points with a slight change:

Win in points by 12-25 you get +5 bonus pts
Win in points by 26 or more you get +10 bonus pts

Without making this more complicated than it needs to be, I have given this much thought but please tell me if anyone differs. I will adjust scores according to these changes and do the current total with this as well but will not feel bad if there is enough contrary to the contrary. . . really.