Seems as though SS doesnt show up in any preview, just quietly does its thing in the prints. Also seems to be directly related to the amount of USM you use so its hard to say just how much SS adds, saving that experiment for the next time i want 2 8x10's of the same photo.
I think what you asked for, a ways back in this thread, was a "print preview screen" which might then show the addition of Smart Sharpening. However, I think you would still be frustrated and/or disappointed since it would not be the same size or resolution as your paper printout. Usually, as I test print through 4x5, 5x7, 8x10 and 11x14, I have SS set by the 8x10--not always, but usually.
BTW--if you are showing/selling you can mark thes smaller ones as A/P and sell them too. Sometimes I just give them with the big print and they realize you spent time and money getting their print right.