I was lying in bed and came up with a way to do it with the manifold.
A 1/8" NPT to 1/4" compression fitting would do it. Actually, an even larger compression fitting would be better. Say 3/8". So Swagelok SS-600-1-2, or equivalent. Then you do a tube adapter. SS-6-TA-1-2, or equivalent. Go to swagelok.com and type in those model numbers.
That way, the only thing that has to turn is a single nut. This will be a bit costly, but will allow you to securely fasten all 3 or 4 of those valves to the manifold, and they won't have to turn. I wouldn't suggest this method for several reasons, starting with expense, but it would work, and you'd get the streamlined effect you're looking for.