Is it okay for a retired (disabled) marine to wear dress blues to give away the bride?

I've never had a real relationship with my father, so I'm thinking about asking my uncle/godfather to give me away when I get married. I have this image in my head of a beautiful outdoor wedding, the perfect dress, and my uncle in his Dress Blues. But I know there are restrictions for wearing it. He served during the First Gulf War and has since been diagnosed with Multiple Sclerosis. Due to this crippling illness, he has lost a lot of muscle mass and is relying on a cane more and more. I'm not even certain if his Blues would fit him as snugly as they should, and I wouldn't ask him to purchase replacements. Can they be tailored? I want to make sure that it's allowable before I ask him to give me away.