Tami,
I would like to help but i have to speculate on just what the conditions are in the senario you are asking the dog to work.
Ist I don't know what the time frame is for the person missing. If your dog has worked trails this old sucessfully then why not try her. However be honest and let them know what she is capaable of doing. If you are not comfortable doing that old a trail turn it down.
Don't pass her off as a cadaver dog. Be honest and up front with your host. You and your dogs will benifit from this in the future.
@nd As to starting a 7 year old dog for cadaver is a dicision only you should answer. The actual working life of most Bloodhounds is about 9 years. It may take a year or more to make her into a novice cadaver dog. Don't expect a top grade cadaver dog at this point of her life. If you approach it as a training project for you to learn her to train a cadaver dog -- fine do it. make your mistakes with this dog and your next dog will benefit from this effort.
If I can be of any help let me know. E-mail me at natalietol@aol.com
Bill T.