Ironworks seems a way to boost this easily, plus the techs that boost mines and the like.
Going no Internal Trade routes makes things trickier, but I suppose we could use food trade routes to get to a big size first, then stop them.
All in all, on Settler difficulty with a fed high population capital, an Ironworks and the right techs, plus a load of mines, its shouldn't be hard to massively exceed this, and we could do even better if we deliberately avoid Industrialisation for as long as possible, build a food city, and then retool it for production once it reaches mega-size. But that would seem to be somewhat artificial... If we're looking at max production per tile instead, the best way would be to make a megacity, then deliberately starve it down to 1 population for a stupidly efficent capital-tile only.
Care to set a turn limit or conditions to the challenge?