In case this has gotten lost or forgotten over the years, some time ago we linked distance from capital penalty to apply equally to allies' capitals, so if you're conducting a war in support of a friend, you shouldn't have any problems with that particular nuisance.
(I recognize that there are other impediments to long-distance campaigns, and have Thoughts about how to address them, but as yet no solid Plans.)
Where mostly talking about heading/colonizing west and away from everything, including allies.
Increasing distance from capital range for these penalties would be particularly interesting for Dwilight.
