Just as an alternative, I tend to use a 3/4 WIDE mat rather than the 3/4 length one.

I find that if I want to be compact then it isn't the diameter of the rolled kipmat that bothers me as you can usually get this down pretty small anyway (I use a Brit Army Issue Kipmat which is about 10mm thick). I found that when on top/bottom of a bergen (the usual place to carry a mat) it would stick out either side when the side pouches weren't being used. I have cut it down from to about 45cm and I don't find I roll off it at all.

My sleeping system tends to consist of a Gore-tex Bivi bag with diaganal zip with the roll mat inside and then my bergen at the head end to keep the bag off my face and then a sleeping bag (usually Snugpak Softie 12) inside the bag. This has worked quite well and keeps all my kit pretty dry. By having the rollmat in the bag it does leave the bivi bag open to ripping by stones or anything but this hasn't happened yet and I tend to clear the ground well anyway. It also stops me rolling off the mat quite well as the sides are kept taught by the triangle created by having a British PLCE Bergen at the head end.

Just a 'different' view on the cut-down thing.

Rich