White crease marks on my turtle neck (not my jumper).

Now that I have spent a few afternoons reading outdoors I have already got a bit of a tan despite wearing sun cream. The problem is that I always get white lines where my neck is creased. It looks awful! A friend suggested applying make-up, but I don't often wear foundation on my face so it might look odd. Has anyone ever used self-tan and would it work on just the creases? Any other suggested remedy or prevention would be appreciated.
Perhaps I need one of those foil reflector boards, but it would be no good when tilting head forward to read.