If it was only in the clearcoat, you could have flatted the surface back with wetndry to "smooth" the scratch out, then gradually get finer, then compound it up (Personallly I use 3M products) either way well done

Often people use a angle grinder/drill type thing to polish panels more quickly, but decent ones are expensive

Rick, you could try mixing your G3 and G10 together when doing it by hand, that way you will "sctratch" less, but still cut back a little