Later I managed to snap a (literally) long shot of it from about a mile away, but with a 200 mm lens, I couldn't capture much detail. Zooming in on the shot as much as I could, it's obvious it's an USAF machine, but I couldn't see which squadron. The tail band was as shown below (mind the distance I shot it from):
I went through the pics in the db, but it appears that most KC-10s have blue tail bands. The only different one I saw was the McGuire AFB one, yellow font on a black background.
Does this a/c belong to some squadron not yet photographed or is it, more likely, a McGuire-based AFB whose band is distorted by the distance?