I think it would be an amazing feature. The same you mark the amount of installations, you could set the amount of mineral you want to move...
Thanks.
It would also remove pretty much the last reason to use government freighters. Commercial shipping
already does too much -- the intent was to have it as a small adjunct outside the player's control. Instead it became the default, and generated way too much wealth in the process. Hopefully, by the time C# Aurora 2.0 comes out it will be fixed.