We got ours too. I can just watch her when I stuff it and give it to her. She doesn't chew up rupper toys so far anyways. We have a large and medium Kong already and she always prefers the medium.
Yep, apparently, despite asking how much your dog weighs, they're only sending out the one for dogs up to 35 pounds. Actually, it's a pretty good size to stuff for Caleb. He's not a massive chewer, either.