Just to close the loop, we tried my proposed Memphis detour above and it was not efficient. Olive Branch itself is a suburb of Memphis with a redlight every 500 feet. On the other hand, the drive from West Helena up to I-40 on US 49 was delightful - good road and virtually no traffic. The redlights doubled the extra time.
ON the way back we again crossed at West Helena but took US 4 across Mississippi to get back to US 72 in North Alabama. This was good 2 and 4 lane roads thru the back country, and a very pleasant and relatively quick drive and only 1 town of any size.
Overall a wonderful trip. 4400 miles and 23 days from north Ala to Utah and back.
