To be fair I don't disagree with the splitting of the army to 3 corps, Longstreet at times was commanding up to 5 divisions and any one time and becomes almost too wieldy to handle. I will say I have kept Longstreet's corps at 4 divisions and just kept the other two corps at 2 divisions, I know it wouldn't of happened, but I also think keeping JEB Stuart in command of one of the infantry corps may have been a solution, then you could promote Hampton to command the cavalry.
Longstreet's Tidewater Operations deprived the ANV of two divisions and, when Lee urged back his top-subordinate, Longstreet didn't managed to reach the battlefied of Chancellorsville in time. The expedition at Suffolk slightly damaged the trust between Lee and Longstreet.
The splitting of the army could have been made in November 1862 but D.H. Hill would have been next in rank to Longstreet and Jackson. So the army kept his two-corps structure until mid-1863, when Lee realized that he barely could fight the Army of the Potomac without his whole force. The Third Corps allowed Lee to reduce Longstreet's initiative while transferring a veteran division under A.P. Hill, one of his favorite officers.
There is already an existing thread about "No A.P. Hill's Third Corps", and therefore I think you can take a look on it by using the search bar. Douglas S. Freeman, Lee's biographer, explained quite well the situation Lee faced when organizing his army before the invasion of Pennsylvania : Stuart was kept at the head of cavalry because Lee thought no one could perform a better job, Ewell was chosen because of Jackson's praises and A.P. Hill deserved his command after having led the largest division of the ANV and for having saved Lee's force at Sharpsburg.
The solution could have been to keep a two-corps structure with a huge reserve division commanded by either Ewell of A.P. Hill and directly under Lee's command :
Army of Northern Virginia
- - - Reserve (Ewell's/A.P. Hill's) Division (6 Infantry Bdes)
- - - Cavalry Division (4 Cavalry Bdes)
- First Corps (LTG Longstreet)
- - - McLaws' Div. (4 Infantry Bdes)
- - - R.H. Anderson's Div. (5 Infantry Bdes)
- - - Pickett's Div. (4 Infantry Bdes)
- - - Hood's Div. (4 Infantry Bdes)
- Second Corps (LTG Ewell / A.P. Hill)
- - - Early's Div. (4 Infantry Bdes)
- - - Johnson's Div. (4 Infantry Bdes)
- - - Rodes' Div. (4 Infantry Bdes)
[- - - Heth's Provisional Bde (2 Infantry Bdes), from North Carolina]
Nevertheless, if the battle of Gettysburg still be fought, Longstreet has enough mapower to try his flanking on the Union left wing, while Lee can assign the Second Corps to the center and the reserve division to the right (originally, A.P. Hill's Third Corps on the center and Ewell's Second Corps confronting the Union right wing).