If you want to ride in this un-sharable lane, you'll need to make it clear to motorists that they will need to change lanes. (or slow down to your speed behind you) Right tire track is sometimes not far enough into the lane to do this.

I'd default to a foot or so from the center. No traffic approaching from behind? Left of center. Then when someone does approach, I'll glide a little right as they start to change lanes to give us both more room. Never would I be more right than right tire track, and I wouldn't be there for long.