I read a post somewhere that a tank could be coated using a heavy mylar and an innocuous oil such as canola. A film of oil is put over the whole of the tank wall surface and then the cut to fit mylar is put over the oil. Bubbles and lines are removed the same as installing wall paper. This is easily removed with no scraping or chemicals required. I have not tried but seems reasonable to me. Now, as to the never get at the back of the tank again issue, the oil and mylar may not be a good choice. If for some reason, which I cannot imagine, the mylar started to detach from the tank you would be FUBAR. Therefore, Krylon is likely the best bet. This stuff is toxic so mask well, including over the top of the tank, and clean very well after the paint is applied. For safety, I would mask everything that is NOT going to be painted.
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. - Albert Einstein
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