historian, but one who has studied Gettysburg for nigh on to 60 years (am I really that old?), I have to disagree with your assessment of Lee's strategy - and Lee as a strategist. Indeed, I am inclined to think that while there was no way the1863 invasion of the North could have succeeded in forcing a negotiated peace, IMHO Longstreet's proposal came closest. The Longstreet campaign plan had the possibility of tactical success; I don't think giving battle at Gettysburg as Lee did really had such a possibility. I am also inclined to think that even with Stonewall Jackson, Lee would have failed. The Union had tactical commanders who were as good - or even better than the Confederates. In Meade, they had an operational commander who was certainly up to the job. Meade had the advantage of terrain, of intelligence, of numbers, and of fighting on home ground. He also had tactical interior lines.
Over time. I have come to the conclusion that Lee was a good and inspiring tactial commander, perhaps even a good operational commander, but IMO no strategist. In many of his successes, Lee was an opportunistic gambler who got lucky. In the Gettysburg campaign Lee's luck ran out, in part because his "strategy" was flawed.
Well, I guess that will provoke a reaction from any "old unreconstructeds" and partisans of Marse Robert. Still, the point of the staff ride in this context was not so much to debate the historical example but to get folk to think about the kinds of problems that might be useful in present circumstances. You raise those questions. Is there an analogy between Lee's Gettysburg campaign and the Marine incursion into Helmand today? If so, is Lee's solution more apropos than Longstreet's or vice versa? (All with the caveat that - as Neustadt & May argue - analogies of all kinds are suspect and must be used with great care).

Cheers

JohnT