I've archery hunted elk in 410. Missouri Breaks are one of the best either sex rifle draws in the state. Hard draw for sure especially a NR. Congratulations.
Good elk population and normally are spread out though the Breaks and herds well up and into the sage hills. And hunters will have the herds on the move.
As you will find out when your there, that many hunters will simply drive the trails, stop, glass and drive some more.
If I were you I would study the maps, and google earth. Find a place where you can get at least a mile away from ANY wheeled traffic. Hike in, there are some BIG bulls back in the rough stuff.
The meat pack out is tough, well worth it.
There will be guys around with horses for hire, good idea.
Bring cash, LOTS! they don't take Visa and they don't take checks.
A great adventure is to go in by boat. Take CMR road 201 (North side) to the boat ramp or Crooked Creek on the South side. That way you will always be hunting uphill and packing downhill. And the pack is often not all that far. Best of adventures to you.
pm me if you like.