i will be very surprised if this works well, if at all. if its that small and you dont mind the loss of a few mls of fuel capacity i would just use filler or 'bog' there are high quality fillers out there these days, that are very good. the one i use is a Ktech brand which is what the professionals panel/crash shops use, well actually these days on cars they just replace the whole body pannel with a new one! at work we will knock the really big dents out though the filler or tap hole or if really need we cut the whole base of the tank out to get the dents out.