Six feet is not long as all IMO to be on the bars. I bet some Stockers and S/S cars ride them close to the 60' mark, or at least set the front wheels down in that area.
Try to tune the front suspension so that it keeps loading of the bars to a minimum. I don't look at being on the bars as a frictional deal, rather if your on the bars too hard or too quickly, it can unload the back tires and spin when the front end comes up the highest on the bars. I experienced that myself first hand.
http://www.qis.net/~geislert/PSI_semi.wmv
As you can see, mine was on the bars probably close to a car length, or 15' or so.