I bought a new dishwasher. The old one was attached to the granite
countertop via two machine screws and metal "brackets".
These brackets are nothing but a metal square with a fixed nut attached. The
bracket is mounted under countertop with some epoxy, then a screw goes
through the dishwasher clips into the nut. Real easy.

In their infinite wisdom, dishwasher manufacturers decided to not have a
standard spacing of the clips. The clips on my new dishwasher are about 4"
further apart. So, now I have a few options.

1) Install a second set of brackets besides the old one. There is plenty of
space for this, but (a) I don't have any of the brackets, and the local home
improvement store doesn't seem to carry them and (b) what if I ever need to
install a dishwasher with yet another clip spacing?

2) Install a wood rail (with epoxy), then use a wood screw through the
dishwasher clips into the rail. The nice thing with a rail is that I don't
have to worry about a bracket being in the exact right spot. However, the
existing brackets make it difficult to install the rail, I'd have to route
out some pieces so it fits snug over the brackets. This is still preferable
to taking down the existing brackets, the epoxy is very tough. I'm not crazy
about wood though. It will be a damp, warm area (steam), so the wood would
need to be prepared with a good stain and or/ varnish. Also, wood screws
tend to loosen over time, whereas a bolt/ nut is pretty much permanent.

3) Install a metal strip (1/2" wide) using the existing brackets. This strip
would be long enough so that I can drill holes at the ends of the strip
where the dishwasher clips will be attached. It's easy to install (plenty of
room between dishwasher and countertop), uses a bolt & nut, and best of all,
I can drill additional holes in the strip should I replace the dishwasher in
the future.

My only concern with the metal strip is that it's slightly flexible, i.e.
will "give" a little. But...we're only talking 2" beyond the bracket.
I checked out what's available in the hardware store, I could go either with
aluminum or steel. Aluminum is lighter and easier to use, steel is much more
rigid but more difficult to cut to size etc. I didn't measure the thickness,
but it's about 3 credit cards thick, pretty solid.

Should I be concerned about not having the clips mounted against something
not completely rigid? Is there an option 4?

Thanks!