I like to use a 50-50% mix of denatured alcohol and water in a spray bottle for cleaning, it cuts the greasy fuel residue and drys fast, doesn't seem to bother plastic covering at all.

I try not to get any in the carb, but I do spray it on the engine with the throttle shut it gets all the surface oil off I wipe the plane and engine off with a couple of paper towels, the plane and engine is nice and clean.