I don't know if you can bypass the new JD's or not. Even though they have that switch to allow you to mow in reverse, it's a damn pain.
My 345, or I should say, the wife's 345 JD, I was able to bypass everything. The seat just takes a jumper wire. The backup took a jumper wire. On my dads Toro, IIRC, I moved the switch so that it would not make contact in reverse.
IF you have small children around, I would suggest NOT bypassing the reverse mowing mode. No matter how careful one is, a small child can be behind you before you know it. I think it was two years ago, in Cincinnati I believe that a father backed over his 4 or 5 year old daughter and cut her feet off because she ran up behind the tractor when he thought she was in the house.
Me.....we don't have any kids around, so I unhook all of the safety stuff.