In my reading of the rules, If that Musto skiff got in the 3 boat zone first he can hold you to his best seamanship (work out what that is yourself) in a 45ft circle around the mark, after that it is windward gives way to leeward and you take him up head to wind if you can but at no circumstance can you hit him to force him up. If you sail with him regulary show him your red flag before the mark or on the beach before you go out and tell whoever is watching the course to pay attention to your boat. That is all you can do.
An important part of the rules is that an F18 can have its bows 8ft out of the Musto skiffs 45ft circle but hold the rights as the F18 has a 54ft rights circle around the mark. This positioning is very difficult to prove off the water but if the smaller boat is level with the big boat then big boat holds the rights.
This could be a very difficult concept for dinghy sailors to understand especially if they know all the rules already like FDUB