Fake It ‘Till You Make It
This is where products like fake keys and clever hiding places come in handy. I would suggest taking to sites like Amazon to explore this world. There are also several independent makers of these kinds of products. The overarching goal is to make things hidden in plain sight.
Thieves will go out of their way to look for something they cannot see, but if they can see it and it looks like something else, well, they might have such great luck in this instance. I would suggest getting creative with this one and using pulling out all the stops, especially if you have plans to go on vacation in the near future.