Face down in your own inventory

Hello I'm playing a game where cards have a basic shared effect when they are face down and when you flipped them they have an extra effect.  Sometimes a player will draw a card face down. Then at some point they will have to flip it face up, maybe later they will have to flip it face down again. I don't think this is possible right now, as you can flip cards but only when they are played on the table, and you can stop players from seeing other players cards (by showing the face down version) but a player can't flip a card on their inventory, or just visualize it face down if I'm mistaken? The only solution I could come up with is by having a space in the scenario where they can drop their cards face down, but for 5 players, having 5 spots, gets a bit messy and I rather just handle everything through the inventory itself. Hopefully I'm missing something! Thanks :)

Unfortunately, you're on the money regarding correct capabilities. You could have one deck of face up cards and one deck of face down cards, and swap between them. There would be some manual management steps for the GM, but it could let you have the functionality. 

Not realizing this was about cards, when I saw the header I assumed it had to do with someone overwhelmed by the frustration of asset inventory management.  :-D

@Aardwulf actually I thought I named it "Cards face down in your own inventory" but I must have deleted the "Cards" bit at the end :O @The Aaron that's what I thought :/ thank you though!