I've found cutting side nocks is the best way of tillering a warbow. It doesn't affect the back of the bow at all, and while the tips are wide you end up getting rid of it all anyway when you come to do the actual nocks (which should be side nocks anyway, if you're making a real warbow
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What's nice about sidenocks early on in tillering is that if the stave does have a tendency to roll over on you, or looks like it might you can pick the side you want the nock on, to counter it.
I did sidenocks for the long string tillering of a heavy bow a while ago, and haven't looked back since!