Stripped screw in fuel tank 1000DS

Hi, I am trying to get the fuel tank off my 1000DS 2004 so I can attempt a weeping fuel repair somewhere under the riders seat position. An allen headed screw on the centreline of teh bike above the rear wheel is just turning and not undoing. Am thinking I may have to grind off the head. Anyone done this before? I was wondering about the heat transmission along the screw into the nylon tank.

Also, what have people had any success with in sealing tank leaks on these plastic tanks please?

thanks
Andy

Yes…this is a picture of one where the screw was successfully removed to illustrate where it is!