I tried this but ran into a problem.
When I look at my inventory using the pip-boy I can see my store bought cards as well as the deck that whats-his-name gave me.
When I open a container I can see my store bought cards and put them in the container but the deck from whats-his-name does not show up in my inventory.
Has anyone else run into this?
You can't see the deck itself it in the container or barter screens. All you have to do to get the cards into your deck is place all of your store-bought cards into a container and then take them back out. You don't even need to close the container. Just click them on your side then click them on the container side and you are done. The next time you play a game of caravan with someone you can see the new cards in the cards list that you get to scroll around through before the game starts.
I would love tips on how to be unbeatable at Caravan, if you have them. I found the text description of the rules a little hard to follow, and there was no tutorial or in-game instructions when actually playing the game, so I have no idea what I'm doing. Wish there was something like how Red Dead Redemption walks you through new games...
Remember you can play a lot of cards on your opponent's side too! Want to clear one of his contract bids? Just plop a Jack on the first card.

I win a lot doing that.