I haven't done Plastidip myself, but there are plenty of guys who have used it on their bikes.
For your windscreen, there should be no issues, but for the side pieces you mentioned, it will wear off, and rather quickly, especially if your legs are rubbing against them.
If you really wanted a good finish, I would sand them back and paint them properly. Plastidip should be considered as a temporary only.
2010 Kawasaki Ninja 650R ABS Island Metallic Blue. Yoshi Exhaust, Sport Bars 3.0, CF Rimtape, Bar ends & Spools, Givi & Ventura Luggage, New Ninja Decal, Double Adjustable Levers, Frame Sliders, PC5 Power Commander, Pirelli Angel Tyres, and more to come!!!