An idea. Unlike the sill itself they are not structural, even at the rear.
(I know modern cars do have bonded structural panels but they were designed
for them.) I don't think warping is a problem as long as you use widely
spaced tack welds first then gradually fill in, instead of starting at one
corner and working round with seam weld or the finished spacing for 'blob'
welds. What *is* a problem is the greater spread of heat from repair welds
as opposed to the original spot-welds burning off the primer on the inside,
which unless you carefully treat the inside afterwards is what causes repair
panels to rust through again much quicker than the originals.
----- Original Message -----
> I have also been thinking of using the panel epoxy so as not to undo
> any rust preventative with the heat from welding and warping along
> the horizontal seam.