Hmmm....., where do I begin?
First for JB1 ; The pivot system you mentioned is the best way to do it, and its also how I did mine. I have momentary switches mounted on a plate that the paddles also mount on. When you pull the paddle back, it pushes the switch in. The switches "click" or "snap" when they engage and disengage. You not only here it, you can feel it in the paddle.
Dratts, I faced the same dilemma when designing my system. I think mine is a little more complicated than yours, but what you need to do is have a secondary "safety" switch that must also be pushed to go into either park or reverse.
On my system, the paddles control the shifting, whether its from park to reverse, 1st to 3rd, neutral to park, whatever.
When the car is in 1st, 2nd, 3rd or drive, there is always power to the paddles. There is no power to them when they are in Park, Reverse, or Neutral. You have to push the center button on the E-gear plate to supply the paddles with power to shift through those gears. I did this on purpose so if you were driving and accidentally hit the wrong paddle or at the wrong time, the transmission wouldn't accidentally shift into reverse when you were cruising along at 65mph. You have to consciensly hold in the button to select those gears. When the trans is in Drive, a relay that supplies power to the up-shift paddle is de-energized, cutting the power to that paddle. When the trans is in Park, the relay that supplies power to the down-shift paddle is de-energized the same way. I didnt want to be sitting there with car in park, reving the engine, and have it accidentally shift into reverse. The system is designed so that if you lose electrical power, nothing will go haywire. I didnt want to driving along and have a relay fail and have it cause the trans to shift, so I designed the system to be "asleep" all the time you are driving, and only come to life with a paddle command.
JB1, I will pull my steering wheel off and shoot a video of my lever system, hopefully it can be of some help for you. I have the switches if you need them, and I will show them in the video also.