Re Seanachie's comment: " Is there a way to get a DEFINITIVE answer to this question? I have been burned once on getting the wrong tartan and certainly would love knowing the real answer." I must agree with Mookien's response. I think there is enough information and there are enough kilts out there that one can simply choose the tartan he/she prefers. There may be another factor to consider when making your choice - preferred weight of the fabric. Isn't the Strathmore USAF-Unofficial woven in 11 oz weight? (Please correct me if I am mistaken about this.)
I also agree with previous comments about weavers' creative license to change tartans. That's just a fact of life for us. In my own case, one of my tartans is the MacTavish Modern which I have in Lochcarron 16 oz. I ordered a fly plaid about a year after getting my kilt, and it matched perfectly. My kilt is a very good match to other MacTavish Clan folks who also have Lochcarron 16 oz MacTavish Modern. However, we all know that we can't count on tartans woven from different runs matching exactly, nor can we count on the same tartan woven in different weights to match. At the same time I ordered my MacTavish Modern kilt, my wife ordered a skirt and sash woven in MacTavish Modern in Lochcarron's 11 oz fabric. Her tartan is noticeably different. The set is different and the blues are different colors. Yet both are MacTavish Modern from the same mill. So, again, I say it boils down to getting the tartan you prefer. Until the USAF recognizes an "official" tartan, it's all a moot question. Even if that ever happens, those of us with existing kilts will have tartans that can proudly be worn as a representation of what was used in a given period of history. If the USAF ever does authorize an official tartan, and it differs from what I have, if it bugs me enough, I'll just have to get another kilt... throw me in that briar patch! <grin>