This is a very basic question but it comes from someone with little
experience.

I am in the process of removing my gas tank (leaks when full, found lots of
information in the archives - thanks).

Both of the 13mm bolts holding the support railings were rusted on.  The
first came off relatively easily with penetrating oil.  The second though
is proving too much for me.  I tried penetrating oil, and then a
hammer-the-back type of impact wrench, but have only managed to round off
the bolt head.  I don't think I could get a pipe wrench on the bolt, even
if I had one.

What is my best next move?

Thanks for any advice.

Norbert Froese
Vancouver, B.C.
84 Westfalia