You have 56moa in the scope that makes a 28 top and 28 to the bottom. If you use a 15moa bases you still have 13moa to the bottom. Like you said it take 38moa with a 200yds zero to get to 1k and 42moa w/ a 100yds zero. The key is to get the reticle back to the center of the tube. The reason for this is to achieve the best possible image out of the scope.Why would he need that much cant???
The 15 MOA base works for me, and it keeps the scope low enough for a comfortable cheek weld.