I've seen a lot of RV-10s and don't recall having seen anyone use tinnermans there -- I certainly didn't. Doesn't mean you can't, but there's really no need since those screws aren't removed a whole lot and hopefully never after the plane is finished. IMO cosmetically you want those screws to "disappear". YMMV....
I used stainless tinnermans where the 4 bolts go through the door. I felt that the tinnerman washer spread the load better on that small section of the door skin. Probably unwarranted but that's what I did. As far as the screws disappearing, the washers will too when they are painted...