When searching for that link, I found a few entries where Doug did some mesh designs for a possible NX refit, had the series gone another season, adding an engineering hull.
It wasn't something that was ever actually planned for the series -- more like what Drexler wished he could've done to redesign the ship if he'd been given free rein and hadn't been required by his bosses to mimic the Akira
I don't think it's likely they ever would've made such a major change to the ship's design in the show itself. For one thing, the shape of the ship is an important visual signature for the show, and it would be important to keep it recognizable. For another, if the ship were radically changed, they couldn't use any stock footage or FX elements from previous seasons, and that would've made the FX more expensive -- and with the show's budget getting slashed in each consecutive season to compensate for sagging ratings and rising cast/crew salaries, the last thing the producers or the network would've wanted was a change that made the show more costly to produce.