depending on the thread depth on your hub, it is also possible to put a spacer behind the cog. i run a 1mm spacer behind an EAI cog in order to use a road double with the chainring in the outside position.

in my case the cog threads are essentially level with the face of the cog, even with the spacer, and the lockring threads actually protrude beyond the face of the ring...thread engagement is essentially unchanged with the spacer. i've put maybe 3k on the wheel set up this way. no issues. ymmv.