As you stated, everyone deals with death differently and what doesn't work for some, works just fine for others.
I wanted to add that I don't think 5 is too young at all. My children, who are now 5 and 7, have seen way too much loss in their short little lives. Unfortunately they already know about death, suicide, depression and more…yippee! NOT. ;-)
But, we don't shy away from death or funerals. My kids are not scared by seeing the bodies in the casket. When my husband's grandmother died, they walked right up and touched her and told her goodbye, and honestly, they barely knew her. My niece, when she died at 16, was cremated and so we then talked about that too. My brother has her cremains in a pretty box and my kids aren't afraid to touch it and talk to it. They have even hugged and kissed it.
Kids are incredibly resilient and eager to learn about the world. I think exposing my kids to these things is only helping them cope with death. Of course I don't want them to have to deal with it at such a young age, but when people die, they sometimes just have to.
If your kids see you handling the funeral with a matter of fact attitude, they will too. If you aren't scared, your kids might not be either. It's okay to cry, it's okay for your kid to see you cry. It's all okay because it's life.
I wish I could have sheltered my kids from the tragic death of my niece and of the saddening death of their great mothers but the truth is to do that would mean to avoid relationships altogether and that's just no fun.
Take your kid, let him see her body, let him know that it's okay to be sad and it's okay to say goodbye. I'm sorry about your Aunt, may her memory be eternal.