Sitting tanks on carpeted cement

[Wulfyn]

Seeing as the cement has low spots and tanks not sitting flat leveled, I asked one of the lfs what they suggest. It was suggested to just shim the tank as it has bottom trim and to not do the styrofoam method. Has anyone have experience with having to shim a tank on carpeted cement? 55g btw. I am womdering if shimming every part f the trim not resting on carpet is in order or not.