The only way I think you could do it without having a weekend is to do similar to what I am doing - an 8 night BA Club Europe Holiday (with car hire). A separate nested booking from my destination back to the UK in economy so I can work as normal during the week with a return at the weekend to pick up the return leg. I'm doing this to Athens but it should work everywhere although you will be in the air a long time. For me that's 320 TP (160 * 2) + 40 = 360.

So for you that would mean your work trip would technically stretch over the weekend (assume you would add the car hire to make it a holiday) but you would actually fly back for the weekend on your own dollar in economy or whatever returning to ORD to pick up your delayed return flight.