mystic is right, glaze putty will eventually crack if put on to thick. It is for pin holes and scratches. I would think If the tank wasn't damaged ( dent) then once you put bondo over the badge area to fill it in, all you should have to do is sand then block, block, block and more blocking at an angle. Most waves come from not blocking enough. However, we don't have your tank here so its only a guess. But I would suggest spraying a light skim coat of black primer and this will show you where your work needs to be done while blocking.
