Mod for adding/removing all fuel

I've been working on some new SSTOs lately and its always tedious balancing wet/dry CoM and CoL. There has to be some quick way to empty/fill all fuel tanks right? Am I missing something in stock or is there a mod that adds this functionality?

Edit: in the spaceplane hanger, not during flight. I understand RCS build aid used to show dry CoM, but it's not updated for 1.3 correct?