Another option might be to learn to shoot left handed. It is tough to do but with eye patches at first and lots of practice it is possible. A cross over stock is another possibility. I am left eyed and right handed but probably should have been left handed. I can shoot from fixed positions from either shoulder but it doesn't transfer over to shotgunning.

A thumb hole or vertical grip stock will help some but it is not a vast improvement. Three to six ounces of fishing weights would reduce recoil more. Or a big scope.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli