my mini kitchen setup includes, from left to right, an 18" dishwasher (yes, they make them in that size, believe it or not) and a 27" sink.
my question was: where should i horizontally position the drain rough-in in the 45" bay ? my common sense tells me in the very middle below the sink basin BUT what confuses me is that the plumbing book that i have gives an example for a 36" CABINET (stupidly, without specifying where in that cabinet the sink basin is, duh ) where the rough-in is 12" from the left, so not exactly in the middle below the basin in any scenario (e.g. of a commonly sized 30" sink).
You're only going to have one trap under the double sink, and since the dishwasher drain hose connects to the dw-connection tailpiece above the trap, it makes more sense to put the trap under the left sink nearest the dw and the drain connection from the trap on that side, too.