I like that idea, but what it comes down to is just being a volunteer at the shelter and working with the shelter to let them trust you to a little more with a particular dog such as take it off the property. The shelters are going to be real careful as to what they allow due to liability issues. Say you take a dog off premises and it bites someone. One of our local shelters actually sponsors an club for kids who get involved at the shelter. They do dog washes in the summer at the shelter and a local pet store as a money raising event. I think your best bet is to get the particular shelter involved in starting such a club with you where they could help formulate what the members can do.