I could take on the role of Alpha if needed.
I was looking at the story line. The members of the MC are all veterans of some military event during the Vietnam War. Is it necessary for all the characters to have served in the same unit? If so, here are a few suggestions:

1/28/68 [url=https://en.wikipedia.org/wiki/Tet_Offensive]Tet Offensive[/url] (several units to choose from) All of the others are extensions of the Tet Offensive. There are several other engagements than just the two listed below.
1/30/68 - 3/3/68 [url=https://en.wikipedia.org/wiki/Battle_of_Hu%E1%BA%BF]Battle of Huế[/url] (1st Bn, 1st Marines/ 2nd Bn, 5th Marines/ 3rd Marine Tank Battalion)
1/31/68 - 2/3/68 [url=https://en.wikipedia.org/wiki/Battle_of_Quang_Tri_(1968)]Battle for Quang Tri[/url] (1st BDE, 1st US Cav Division & 2nd BDE, 101st Airborne Div)

Pardon me, I am a military history buff. Although, both of these engagements, Hue and Quang Tri are American/ARVN victories, there may have been small isolated pockets of US Army soldiers, US Marines or ARVN soldiers who were vastly outnumbered and suffered a tremendous defeat. We can easily portray one of these smaller isolated units that may not have suffered a tremendous defeat but in some mysterious way outlasted superior numbers to survive with only minor wounds. This is the stuff Medal of Honor citations are written for.