Sounds right, although my experience is with 155s. I know a friend got into difficulties with 168s at 1000y (900m).
The other factor of course is that the 30 or more minutes is up from your short range zero. If some elevation was already used up to get that zero, there will be less left. That is why the pitched 20 moa bases, Burris rings with eccentric bushings, etc. can be useful. You build some elevation into the mount, so you can reserve your scopes internal adjustments to get on at long range.
IIRC, I saw the spec. sheet for Burris scopes, and total adjustment range seemed a bit shy for long range on internal adjustments. With the Mildots, you could use one of the dots as a long range aiming mark, as long as you didn't mix up which one to use. Most scopes will have enough internal adjustment for windage. Many shooters will apply a basic correction, then hold off for minor changes. If the wind is really gusty, or switching, all bets are off. Might be necessary then to leave the scope at neutral, apply a correction or hold off for every shot.