JON Bon Jovi could be planning one day to run for governor of New Jersey. That's why he's keeping his house in Red Bank, even though he and his wife, Dorothea, and their four kids have moved to SoHo. That's why he performs regularly at fund-raisers for Democrats like Al Gore and John Kerry. And that's why he hired p.r. guru Ken Sunshine, who was once the chief of staff for ex-Mayor David Dinkins. "Jon has been approached many times about running for office," said Sunshine, who denied the rocker has any political plans. "His day job is going too well, and this way he can keep the house."