Sure it's possible. It's a little harder to decon your legs when working upper body; some exercises will require significant load on the legs (ex: barbell rows will work your hams a bit.) But you can generally decon, especially if you use a lot of machines, and 17 days is plenty of decon time for your legs. Now you have to worry about getting good upper body decon while handling a lot of 45-pound plates for your legs. . . just try and take it easy.
It occurs to me that this is a good way to achieve nutrient partition even while doing decon; half the body is still in an active cycle and using up the calories. This may get you through your decons with less fat but without the need to vary your calories as much.