I would not bother, but all you really need is the crank and BB if you insist. The rest can be dealt with by careful use of the limit screws.

If you are racing (or in race-esque rides), there is some merit in the simplified shifts offered by a double vs. a triple. The weight difference seems less convincing to me unless you are already as light as you are going to get. That small ring, a half inch of extra derailleur cage and three more chain links can't weigh much.