Basically, I want a mod that from VAB/SPH you can click "Simulate" instead of launch, select from drop-down list of appropriate simulatable environments (on Mun surface, orbiting Laythe, etc) which would then load your ship at the appropriate location and allow you to test it in the proper environment. Of course, it's just a simulation so no matter how well it works you can't save your progress but at least you won't have to fly all the way there just to find out your staging was wrong or fuel imbalanced.