This is probably something for the content creators forum, but how about assigning track sounds to rail joint a fixed track asset?
Simply place the track sound fixed track thingy every 39-40' or wherever else you want the track sounds to be. The object doesn't have to be very big - two joints connected to an invisible bar to keep them together. There would be two connecting circles on either side of them so the track could be attached to them. They could be made in various widths to acommadate different gauges, and could also double as track spacers for double track if someone wants to go that far.
The other thing too is any kind of track sound could be assigned to these rail joint objects such as switch frogs, bridges (like they have already), and crossings. This would eliminate the assigning of generic track clickety-clack sounds to the rails, which can be automatically welded. In the program its self, there would be no need to add extra tags in an option file because by default there would be no track sound. Today it's different because we have to compensate for the opposite, but in the future it could be the opposite.
I'm not an asset creator that can do something like this, but hopefully those that can might pick up on this idea.
John