This is my first season with our trailer so I can't say what I do will work forever but....I don't wrap it with anything. I think it may have had one wrap on it from the factory but I didn't bother putting that back on and it doesn't leak.
The plug that came in ours looks like a nylon plastic so it's kinda soft and seems to seal fine for now, only time will tell.
I plan on putting in some sort of drain because it's a real pain to get the thing back in once the tank has been drained.
2013 Ford F150 SCREW, 5.0, 3.55, tow package
2014 White hawk 28DSBH