Would it be possible to plastic wrap a tester? You could sacrifice one tin of each - take the lid off and tightly wrap with a clear plastic. The plastic would protect from people sticking multiple hands it it like a true tester, but would give them an idea of what the product inside looks like.
On a side note - In trying to pick good packaging for some new products, I'm doing shelf-life studies now with several of my recipes. I really want to go to the paperboard tubes as well. However, I'm finding out that they aren't suitable for some recipes/uses. For lip balms, the edges of the package tends to pick up moisture. I haven't had mold grow on the packaging yet, but the edges of the paperboard start to separate after only about a week of use.
I also have purchased a few products from other small companies using these tubes, and I'm not happy with the way they hold up.
Just wanted to pass this along in case it is useful in your packaging choices!