Generally speaking, The P3 has further evolved into a closed eco-system.
There are no spare channels, there is no expansion buss or nodes.
With the exception of some 3rd party retractable gear there's no real opportunity for electrical modifications.
You'd need to add a secondary control system (a.k.a. car alarm type key fob, etc.) and these are extremely short range.
The afformentioned retracts contain a custom interface module which 'listens' to one of the 'X' channels. Upon proper switching it will activate PWM servos. This has not previously been availabale without the gear and I presume that's still the case. At best this adds 1 channel (sort of).
The gear & module: `$250.
