Need suggestions for getting old gas out of tank

No comment :(
Actually no, this did not happen to me....... On the carshow run to Minneapolis run in 2004; By that time I had had the system bugged out for several years already.
But the story is a collective of all the sad stories I have heard and experienced in 48 years of fixing cars.
I have never found a good chemical to remove that crud in the tank, except accetone. Accetone is far more dangerous than the labelling seems to indicate.
I know a new tank might be about $200Canadian, but for me it has been a no-brainer for quite some time. The liner epoxy coating is very difficult and time consuming to correctly bond to the tank.It is not cheap. And when it lets go, it comes off in sheets, and you are back to square one, and a tow-job broker for it. I use on motorcycle tanks, that are difficult or impossible to replace.And my bosses have charged a lot of money to install it cuz it takes several hours,over 3 or 4 days, to get it right.And I still say a prayer every time I send one out.