If you suspect the short LOP is part of the problem, slip a Kick-Killer leather pad on it and see if it helps. It will add 1/2", and you can make that more by putting "shims" inside it before putting it on. As you probably know, I use them on most of my doubles. Cabela's has 'em.
I use a Galco leather pad and it did not add enough LOP on several of my guns so I cut a piece of 5/8" thick backpack sleeping pad foam to fit inside the Galco leather pad. Together they add a about 1" LOP and this works well for me.
If you need enough of this foam to fit inside a Kick-Killer or Galco pad PM me your address and I'll mail it to you.