It can help but you still have to be close enough to the spine to get the desired effect. Good expansion will always increase your odds vs one that pencils through.
Yep, I hear you! I had a similar high shoulder shot on a 4x4 Mule deer about 12 years ago. An A-Max shot from a RUM anchored the deer. I noticed copper fragments on top of the spine when cutting out the straps. I was glad to have that bullet for this situation. However, this bullet/RUM combo would not have been my choice for elk. It will be interesting trying the LRABs anticipating somewhat of a mix between the A-Max and AB. I won't be shooting the gun next year but a family member will.
Two guns for short to long range hunting? I'm already doing this in most cases when hunting from a hide. You never know what distance the animals will come out. Two different bullets in the two different guns, yes.
My only one gun all around choice for antelope to elk at all ranges, the 338 with 300 OTM. I would consider a 300 LRAB but we all know how available this bullet is, about as available as some of the Bergers right now.