1) 80% for the rest of your life beats 100% for two weeks
2) Good enough is good enough. Really. Perfection is not only not required, but can be very counter-productive.
3) Trust the process. Don't undercut it by putting restrictions on S-days. Just live with it and see what happens over time.
4) Relax about the details. If it's only one plate, don't dissect it, just eat it.
5) As counterintuitive as it sounds... if you're having trouble with S-days, the best strategy is to PLAN a wonderful, decadent treat. That cuts out all the perma-snacking on stuff-that-doesn't-really-satisfy. So...in other aspects of life, consider "what would be most satisfying?"
6) The one-plate rule has the side-effect of putting me in better touch with my body, b/c I have to ask "how full does this plate need to be?" In other words, "what do I want here?" That is a good beginning to asking that question elsewhere. Like, when I'm full and want to eat anyway... "what do I REALLY want here?"
7) It's okay to enjoy treats (on S-days). They taste better when they're truly allowed. (But that takes some getting used to.)

I maintained my weight for years through a sort of armed truce with food - I didn't trust it or myself, so exercised constant vigilance. Now I feel that I've made peace with food, and some of the "lessons" are spreading into other areas of my life.
Some morning ramblings...