I never got my KSP issue fixed, and I'm back at it currently.
Someone mentioned updating the smokescreen for 1.7.3- I found I could uninstall RealismOverhaul, and reinstall it, and with the reinstall came the required mods including the smokescreen. Then I just include anything else that got uninstalled with RO, and I'm good to go. Well, other than the one part which is missing from all my spacecraft.
I think the issue I'm having is related to the RO craft files or RO engines, but they seem to be incompatible with each other. The part I need is, I think, the LR101 engine, which is included in the game, but not recognized by the craft files. It also has different properties than I'm familiar with, so I think the mod I originally found it in was replaced. Correction: The part I used was the TD-339, which is no longer in the game.
Again, my issue is that when I try to load my save, it says vessel "is missing part RO-SurveyorVernier" for almost all my spacecraft (I used this engine a ton), which happened after I updated from 1.6.1 to 1.7.3. I'm using the full RO suit, along with a ton of other mods, but I tried not to remove any part mods when I updated.
I'm going to try digging around in the part files, and maybe try to just make a new part.