Are you sure they don't check SW? When I originally posted this I asked if I can get a lower swingweight. This was the reply from Chris:
We have found an average of 333 swingweight on the RDC with 4G, so you would need to ask for the lowest swingweight unstrung in hope to stay under 330. Pretty much all poly based strings are going to be within a couple of points. A light nylon string might get you down 6 points or so, but I wouldn't want to play one of those strings in the S racquets -- they are perfect for polys.
With that in mind, unstrung you'd need to be under 295, maybe sub 290 to be safe. Our racquet strung with 4G adds 29 points. We just measured it, cut the strings out and measured it again to be sure.
Can someone at TW confirm if they do or don't.