Paul, your photo does seem to match the Altgens line of sight and so we should be able to tell which lane markers you are pointing to for the limo and Chaney's positions. Doesn't Altgens line of sight show Chaney's lane marker to be the one behind the limo marker when you plot it on a map from Altgens LOS? In fact Altgens photo does not show the Thornton sign so the lane marker next to the limo marker is not even visible in the picture. It has to be the one behind it.
By the way the plat map puts the limo lane marker in the correct position but the West map does not. The limo marker was offset from it partner and started about 6 further down Elm.