Alonza remains a "missing" man. But, from what we've already seen we know how sketchy the records can be. It is very possible that no record of his service survived. Overall, my estimate is that the service records from NARA cover only about 80% of the men, on average...with some unit's records much less complete.

As to G.W., I have the following:

HORTON, George Washington, III
Born 11/2/1832 in Pleasant Ridge, which was then in Pickens Co. He joined Co B, 40th Miss Infantry. Died 10/15/1909 in Leake Co., Miss.

That "III" indicates that there was more than one, of course. Maybe an uncle was the "II" and this was the man in the 42nd Ala. Inf.