Seeking name of missing American during Operation Cobra

Hi there, I'm an Aussie trying to solve a mystery for a French family regarding the death of an American. A friend has a family holiday house in a small village on the coast of Brittany called Le Pouldu.( which is in the Finestere local Govt area )It was requisitioned by the Germans for a number of years then they left sometime during the confusion of Operation Cobra. Around this time a young American soldier was shot and killed as he stepped out on the veranda to have a smoke. Not sure if it was officially requisitioned as a billet or not. The story has been in the family for years and as yet no one has dug around for a name so I've decided it's definitely time this young American soldier had a name.

Combat Command B - From initial reading I assume he was with VIII Corps and probably part of Combat Command B (CCA stayed behind at Brest further north) who went with 6th Armored as they headed South to receive 4th Armored who had the Germans surrounded at Lorient. I started to try and break down all the individual units etc and then read there history and where possible try to find and read their official "battle/action" reports but there is so much material relating to Cobra that I have got myself well lost and hoping someone can help shine a light.

Events moved so swiftly at that time in August that there may well be no help in the records however he should be listed KIA although there is a chance details and location were not recorded. As you can see it's all guesswork on my part so am keen for some help