They don't exist. The only way to solve it I've found is separate rug/neck cover and even then I end up with a thin bit of mane half way up the neck. Nothing like the mane loss I got from combo rugs though.
i find shires rugs are fab! i have not had one thats rubs his mane out yet, it lies it down nice and flat but doesnt rub it out, i have one that pulls the hair right out and the inside of the neck is covered in mane, its annoying as its a nice thick rug aswell, but i havnt had a problem with shires yet
My sisters' tb has a weatherbeeta combo, all-in-one neck and it doesnt rub his mane, but I have come to the conclusion its not the rug its the type of mane, sound stupid I know but Iam sure some manes are more brittle than others, when I worked with hunters in Leicestershire they were all done the same and all wore exactly the same types of rugs in stable and turn out, 3 kept all their mane but one by the end of the season only had half a mane and 5 plats!!
My Mark Todd combo never rubs my sec D. His mane was nearly 2 ft long last winter (pulled it this year as got fed up with dreadlocks) and it never rubbed at all.