Yeah, its a shame you cant take that one multiple times, it might make the rogue a bit less hard work.
Does it have to be a whip? Can you achieve the same if you were a ninja rather than a rogue and used ninja reach weapons?
Other than that maybe dip a level or 2 into something else. Bard gives you whip proficiency, Fighter would get you feats and BAB +1 at 1st. 1 level of Kensai Magus would give you EWP, Weapon Focus and Canny Defence and a few spells.