I see your point. Say 50MOA usable needed from a 100 zero with a 338? That would get you to 1500? Thats a pretty good poke even with a 338.
The 8-32 does that with a 20moa base assuming a center range of adjustment with a 0moa mount.
45moa total E on the 12-42
65 moa total e on the 8- 32
Considering the platform I would consider the 8-32 assuming a 20moa base. Ive noticed some of the 20moa bases lift the ass end i mean ocular of the scope pretty high however, making neck strain worse. Be advised ive made many a poor decision doing what I wanted rather than taking sound advice from knowladgable individuals.The 22 is most probably the right tool for the job.