BalCalc is one of those mods that actually patch a hole in the game's mechanics.
I was wondering if you were willing to add an option in the mod installer to set "E" key as the key to lock the distance? If I remember correctly, some very very long ago it was the efault and built-in key. Now every time I install the mod I have to manually set "E", as I use "Q" and "F" for other things.