aircraft stripper has a spary stripper that is safe for plastic, i have used this on sport bike plastics and a few random vintage plastic parts from time to time. it works really good, usually takes it down to the primer where you can scrape that off. that said be sure you try it in a small section and follow the directions. on something as small as a side cover though i would prob go course, med, fine block and then lay an etching primer, block that out, and lay your base coat.
http://www.autobodytoolmart.com/klean-strip-paint-remover-plastic-eup367-p-12820.aspx?gclid=CI3Foe3C2rgCFcef4AodoFYAgg