Hi
You mention pistol "caddy" plan, which implies something completely different than a regular Midway or other commercial zip up, foam padded, zip up case with a Cordura outsides. As long as it's not visible to the "authenticity police", why re-invent the wheel?
Where to you plan on the caddy being carried? If its on the "handle bars" of the gun cart, I'd go with Coffinmaker's idea. That would be VERY authentic, practical, and you COULD use a liner to keep the pistols from getting bumped. Look up Pommel holsters in Packing Iron or Google.
My apologies to the "authenticity police" but I couldn't think of a nicer term that described what I meant.
Mike