Well, I for one think that tartan Argyle hose would not look bad. I completely get what you are saying about it perhaps looking like "too much" tartan, and I might agree with you if the tartan in question were a rather loud or bright one. Then again, my photo of Eph MacLean which you posted shows someone pulling off the look rather well even with a bright red tartan (and a red velvet doublet, to boot!). So perhaps there is not as much to worry about as you might think.

In your case, with the US Army tartan, the overall colors are much more subtle and dark. I think a pair of Argyle hose made to match in this case would look rather nice with the outfit. I wouldn't worry about it being "too much" at all.

Other options are certainly viable. As Glen suggested, red/white diced hose would look great! (And they would certainly "pop" more than tartan hose would). If you wanted to go with more subtle diced hose, you could opt for green/blue or some other combination.

Another point to consider; if you do have tartan Argyle hose made, you don't have to always wear with with the tartan waistcoat. You could wear them with or without, and it would certainly give you multiple options for formal wear.