When I was in the irrigation business full time, I carried one of those big 44 oz cups. I found a 4" pvc pipe cap would fit the cup nicely after I cut a small section out of the side of the cap to allow room for the handle. I then screwed it to the floorboard of the superduty F-250 I was driving.
I was considering doing the same thing in the semi until I priced the cap--they have quadrupled in price!!! I ended up using a smaller cup with the style of cupholder in Czeckman's second picture. I broke off the tab that goes down into the wndow channel and used one of the screws for the ashtray to secure the cupholder to the lower dash of the KW T-800. There might be someplace that you could do the same thing with.
