I used the Badger Ultra-High rings mounted directly to my Bushmaster Flattop for a cheekweld height that's perfect, (at least for my facial structure), with an IOR 2.5-10. If the Warne Ultra-high rings are similar in height, it should work fine as is, without a riser rail.
I would not use a riser if I didn't have to move the rings forward to attain clearance or eye relief. Some optics require them, and if you need to use one, you can and should go with a lower ring height, as Urimaginaryfriend suggested.
The 22 moa rail from Badger would be nice if you need to add elevation bias to a long-distance rig.