With 2 ortho rotations you should be able to get more than 2 letters. Although I was assigned a single preceptor per rotation, I ended up working with way more than one person per rotation, and just selected those that I thought knew me/liked me a little bit to ask. So you should be fine, just find a couple of attendings who you get along with and get some good advice from other folks going into/already in ortho. Good luck and have some fun