Looks good. I would think it will hold up just fine.
As long as you are not bottoming out at all. When we go and I ride with my fat buddy Jeff on the 2 up, we bottom out from time to time, but our joint weight is close to 525lbs.
It is normally just myself on the sled. I do have the springs set tight on the rear suspension for the added weight. I stood on it last night after I made it and it did not flex at all (210 lbs). I sent the sled and trailer with a buddy today to Upper Red Lake for the weekend. I will see if it makes it back in one piece.