I've never extended a bumper, but I've taken them on and off. Typically, they mount to the
end of the frame rails, AND to a point a couple of feet further forward thru the
diagonal braces to the corners of the bumper.
And typically, there is some slop in the mounting holes for adjustment -- and if there
isn't, you can grind some.
So what I would look at as a first possibility, is to add an extension to the frame rail, and
then bolt the bumper right back on. If the extra thickness of the extension
material causes too much trouble, you could extend it twice -- the second
extension returning to the original frame width.
For extension material, it would be nice to use a channel similar to the frame, but... sitting
here in my living room tonight... that seems unrealistic. More realistic is to use flat plate,
maybe half inch thick. At this point, I would stop trying to do everything myself, and let
a steel shop cut the pieces to suitable size AND punch the holes in them. What I think I
would do, is make a plywood template. Take your time, and get it marked just right.
Heck, with plywood, you could even actually mount the bumper. When
everything is honky-dory, disassemble and take the templates to the
Of course, this is easy for me to say, sitting here in my living room with a glass of
Lost Coast's finest Indica Pale Ale and not having to actually do it.