Thanks to all for taking the time to offer their thoughts and experience on this. It's given me something to think about.
Being a bit of a minimalist, I really like the idea of using my existing factory transmitters in a solution. I guess I need to research the hardware that the PT uses to receive that signal from the tire.
Is it built into the vehicle's "computer"?
Or is it a separate receiver that switches on that little dash light?
If it's separate:
Can I get another one from a junk yard and wire it into my coach?
Would it have enough range?
If the "receiver" is built into the "on board computer":
Can I run a wire from the PT dash indicator light to a light/buzzer mounted on my coach dashboard?
(The PT TPMS "receiver" would have to be able to function with the ignition key in the ACC position)
If an aftermarket unit could utilize factory sensors in the towed vehicle while adding additional sensors for the coach, I'd just do that instead. Otherwise it may be worthwhile to play with this a bit.
Again, thanks to all who replied.
If anybody has played with a DIY solution to this I'd be interested in hearing about that too.