Look in the 21-22 foot range. The Gulfstream Amerilite 21MB has all those features. I don't know about the cargo capacity, but it's well over 1000 lb for sure.
Why do you think you need that much carrying capacity? There isn't a huge amount of storage in a small trailer. You will have bedding, clothes, bathroom supplies, food prep items, and food. There is limited storage for all of these items in a small trailer. The only big storage is under the bed. Our Amerilite had the FW tank under the bed, which was nice in cold weather, but chewed up the storage.