Tom,
Number 63 on Gilchriese's map, which is directly in line with the O. K. Corral, is labeled, "Vacant. Sometimes used as back entrance to O. K. Corral." There's more to his description, but this is the key part. My copy of his map also includes an arrow pointing toward the O. K. Corral. Number 62 is Bauer's. Number 64 is the Papago Cash Store. Number 63 is on a straight line with the Allen Street entrance.
There are some errors on Gilchriese's map. This isn't one of them. Your characterization that Gilchriese did not know what he was doing is also unmerited. Gilchriese worked with Bob Mullin in the preparation of the map which was the first serious attempt to provide a map of Tombstone, circa 1881-82, in decades. Look at the Mullin map done in 1949(which I believe you have a copy of) and you'll see the baseline format from which Mullin and Gilchriese went on to build Gilchriese's 1971 map. And don't gainsay Gilchriese and Mullin for not anticipating the changes that other researchers have made to the map of Tombstone over the forty years since. Their research enlarged and improved our understanding of Tombstone, but they did have the benefit of the Mullin-Gilchriese map in the preparation of their own.
In my book, I was one of those who had the Clantons walking through to Fremont and turning down the street to the vacant lot. I now believe that was an error I should not have made. In his book, Casey had the cowboys split up, with the McLaurys and Ike Clanton moving through the rear entrance to Fremont Street, then splitting up with the McLaurys going to the Union Market and Ike walking down Fremont toward the vacant lot. In the meantime, "The two Billys, Clanton and Claiborne, passed through the open corral and entered the rear of a vacant lot next to the two buildings that made up Fly's Photo Gallery and rooming house."--LBL, p. 120.
I think Casey--and Gilchriese--had it right. Since I finished my book, and due in part to discussions on this board, I've modified my view. In fact, I have come to doubt that Tom McLaury was with the cowboys when they passed through the corral, but was, in fact, already on Fremont Street conducting business. Some will doubtlessly disagree with me on that. The evidence indicates that Billy Clanton and Will Claiborne, the young guys, were walking behind the others carrying on a separate conversation.
The vacant lot appears to have been a rendezvous point. Frank was going to take care of business (and, I think, to look for Tom). Frank didn't just go to Bauer's, but walked back toward Fourth Street all the way to the corner. Ike may have also been looking for Tom. In fact, he may have been the one who found him, considering that Ike and Tom both arrived at the lot before Frank showed up with the sheriff.
The youngsters, Billy and Will, with nothing to do but wait on the others, turned behind the businesses on Fremont and walked through an open area and turned again into the vacant lot between Fly's and Harwood's. Claiborne testified that he and Billy went directly from the O. K. Corral "to where the difficulty occurred."--NUGGET, November 9.
Claiborne indicated that he and Billy continued their conversation in the vacant lot. He told the coroner's inquest that they were still talking for fifteen minutes after the others, including the sheriff, showed up. Billy left Will only "after the Sheriff went away in about two or three minutes, and joined the other boys" presumably to find out what was going on.
I won't argue that the "back route" to the vacant lot interpretation is not subject to challenge, but it makes the most sense to me. I'm not even sure that it matters all that much whether they approached the lot from Fremont Street or from behind the buildings. What is clear, though, is that the young Billys were the first to arrive at the vacant lot. Claiborne's testimony makes it clear that he and Billy Clanton were engrossed in conversation from the time they passed through the O. K. Corral until fifteen minutes AFTER Behan showed up. That's fascinating within itself. What were they talking about?
For what its worth.
Best!
Gary