According to Wikipedia (I know the objections you might raise with that) nobody has done that in our main domestic 4 day comp. Rilee Rossouw has the most runs for a season at 1189 and Vasbert Drakes once took 60 wickets in a season. Both Rilee and Vasbert went on to play International Cricket with varying degrees of success. The records listed makes for interesting reading and it seems that making 800 plus runs a season isn't an easy feat unless your name is Barry Richards. Ditto taking 50 plus wickets a season unless your name is Mike Proctor.
All that said, I do agree with the point your making with regards to our domestic system and the need for a strong comp to produce good, well rounded cricketers.