Have you done NILIF with her? I think that before throwing in the towel and crating her when people are over, it'd be good to tie her to you. That way she can still be out, but be safely secured to you and you can issue any praise/corrections as necessary.
I haven't been on the board much lately, so I'm not up-to-date with everything you've been trying, but if you can work with her on this safely, definitely try that before giving up. (And you don't seem like the give-up type).
Just remember it will likely be something you will ALWAYS have to manage and watch.
Ozzy - Chocolate Pom
-Fastest 2012/2013 U-FLI Pomeranian
"In a perfect world, every dog would have a home and every home would have a dog."