Can you bring a backpack

Yes, I'm sure that you can. But, WHY?

Take it in and stael all the small stuff

I'm pretty sure you can bring a backpack. Though, to be honest I don't see why you would need to tour around with one. Most of us left our bigger belongings in the "green room" and just took what we needed. I remember them warning us about footwear.

There were people who toured who had the small light packs, like the nylon and string type pack but I believe they ask that you dont bring a big bulky pack.

I do not believe that was an issue when we were there. Ladies had purses. People had camera bags. If you really need to carry it, I would call ahead of check the website for confirmation.