|David knott 242|
How about Variant Multiclassing? It costs you half your feats but no class levels. You would get Versatile Performance in place of your 11th level feat (a bit late, I know).
I think your best be might be to select traits, feats, and other things that boost your Sense Motive checks directly. There are several magic items that give you a +5 competence bonus to Sense Motive, so one of those on its own is probably more valuable to you than something that switches the stat mod on a skill.