I have found 3M powder guidecoat is the best for those fine scratches for me.
Don't jump from 180 more than 240 or 320 tops. You can sand out 180 with 240 then 320 then 400 if you had enough material and if you guide coated it so you could see them. But as Jim pointed out, realistically, why? 180 is something you use before you prime, to CUT something FLAT. So once you have CUT it FLAT, apply a few coats of primer then with this new FLAT surface you can sand with a finer paper being you aren't needing to CUT it FLAT being it already IS flat.