I was thinking of using a joker lap the other day, and I even designed a circuit... but I was thinking it couldn't be done with existing Scalextric lane change track, except on a "driver honesty" system... LOL!
It is a shame Hornby didn't decide to allow the powerbase to send and receive data to the lane changers... all sorts of possibilities open up.
Anyway, your idea of using the pit pro sensors is a great idea.
I've looked at various options, and this is the simplest I could come up with...
It is based on a PitPro or PitPro Deluxe being used exclusively
for Joker lane detection. If a pitlane is required as well, PCLC should be able to support an additional Pit Pro
(if you have lots of money)
Again, to keep the options simple (too much choice makes for a very complex UI) I would suggest that when used in this mode, the lights on the "joker" Pit pro are used to show number of joker laps remaining (3 lights lit for 3 or more joker laps remaining. A stop/go penalty is indicated by all lights flashing.
Here is my UI to go in the C7042 setup screen
Joker Lap Detection
[x] Pit Pro connected at: [COM4]
Note: this PitPro will show joker lap information
Number of Joker Laps per Race [ 3]
Penalty for extra joker laps
(o) Stop-Go penalty
(O) Reduce power to [ 20]% for [ 30] seconds
There would also need to be a column available on the main display, maybe a picture of a joker with a number overlaid on top, and a joker with a cross through him to indicate no jokers left.
I can't imagine this is a trivial piece of work. Is anyone else interested in this?