Thanks, some good suggestions to check out.
You already implemented some of them -- thanks for that!
I think Autodrive already works with the Boat from Cargo Ships. It's not working for you?
Just tried it: it actually does. However, I looked at the item descriptions in the research tree. There's a list "Placed in:" with some icons (car, tank, different armors). The list also contains the icon for the truck from LJD Vehicles (perhaps because it is unlocked together with the car when Automobilism is researched?), but not the icon of the boat. That's what made me think it wouldn't work.
Also, I managed to confuse the vehicles: Went to the coast in my car, placed the boat on water, and accidentally marked both car and boat with the radio control. Both vehicles tried to get to the same destination. The car stopped when it came to deep water. Then I clicked on land, and the boat started complaining ("pathing … no path … pathing … no path …") until I selected it alone and gave it another order.
The remote control is currently just single destination. "Hey car, go build this outpost" type thing. Might add waypoints, but unsure about complex patrolling -- that is currently more in AAI's domain and already highly configurable.
Too bad! I've not played with AAI yet because (from what I've seen on youtube) it seemed a bit too complicated. My intention was to concentrate on trains for long distance transport on land and ships to connect train networks across islands/continents. Automated cars would be great for the mid game, to pick up ore from patches in the vicinity of the main base that are not far enough for trains. They could also be useful for on-base transport of stuff that is used in large quantities, but only sporadically: e.g. concrete for nuclear reactors (it's not worth it to put concrete on the bus because you don't need it all the time; it would take early bots too long to move that much concrete over longer distances; and the distance is too short to use a train -- a car loaded/unloaded by bots at each end would close that gap perfectly). But I guess that's way beyond what this mod is meant to do. It would probably mean something similar to another railway system (different routes for different vehicles, waiting conditions so they could be loaded/unloaded …).
Well, at least I've found one practical use for the remote control: I could drive in the car wherever I wanted to without bumping into each other rock or tree! :-D