i had the same issue as you did, for the rear add ons, i put my hand at the bottom and just ripped it of, on both sides, leaving all this rock solid fibreglass on my arches, got my grinder out and took it to the arch going to metal in some areas

then hand sanded the remains of, skimmed the area with a small amount of filler, sand it it back to shape and primed it
for my skirts they wasnt so bad, only a little fibreglass filler was stuck to the sills, got my grinder out again and removed as much thick paste as i could, then hand sanded the rest, got facebook? i use it as my supra diary, will be pics on there of how i did mine
to anyone else out there, who gets bored of a look quite quickly....dont go blended!!