TheIV

Isn't Legacy pack outdated? Had Some problems with it couple of months ago and don't use it since. CoM should still be roughly in the middle of your craft or you risk to summon some crazy transsonic flips. It is also obvious that moving CoM closer to front make it easier to move CoL behind it... Can you maybe post screenshot with markers from SPH?

Well, FAR is not stable as of now so I stuck with stock aero until official release. Also OPT needs a patch for FAR, at least there were for previous versions. And on the question of balance - use the power of your creativity: move parts around, rotate them, use more wings at the back of the craft. Add more stability control if nothing helps. OPT parts are OP as hell and that is why I like this mod (RIP mk2 scramjet. You were the awesomest).

Dunno 'bout no stability problems. OPT planes are easy. Here's my Manta series - taxi, bus and delivery crafts near new orbital station. All are ironclad stable during accent (pitch 25 degrees after lift off and chew snaks, don't forget to circularize after though). Descent and landing is also easy enough, even I can manage it after all, and I am really bad pilot, 'specially in stock aero. Modern fighters such as f-15 or russian MiGs and SUs utilize lifting body composition providing up to 40% of total lift with their fuselage.