Otherwise other mods end up with duplicate copies of networks and node_maps.

Which other mods are duplicating the road network?

The one I am writing at the moment, it doesn't have to interact with the transport drones, though that's a logical thing, but it does use the same road network concept, which I'd prefer to hook into rather than duplicate.

Depending on what you're doing, it might already be possible to add it. I added some functions for other mods to add their own custom depots.

One hesitation is letting other mods touch my road networks, they can do stupid things and corrupt the networks, and I will get the bug reports

I definitely feel you there; I will see what the minimum set of functions that could be exposed are, hopefully it will be a small enough set (and possibly read-only) that people won't be able to corrupt the network.