Hi, I am currently trying to crate train my dog. I have small carring crate that I have been using which is perfect for his size now since he is just a little fellow. Even though he hates and goes wild when I put him in he needs to get use to it. I am wanting to go ahead a puchase a large crate that he can use now and use when he is fully grown. What size would you recommend for a fully grown boxer? Granted he is a puppy now but I will block of the rest of the crate until he is large. So what size and what brand would you recommend? Thanks