1 1/2 " is not a "minor adjustment", so if it's what you need I would get it done somehow, no matter what anyone tells you. That's coming from a fellow tall guy who has a reallyhard time shooting off-the-shelf guns--those who thinks it's a non-issue tend to be pretty average-sized in my experience.

If it's a lightweight gun any of the options except adding a thick wood spacer will likely affect the handling of the gun very significantly.