If you're really after the SD storage option, you might want to check on Arlo? It's got both cloud and SD storage option. the cloud will be 7days free. It's small and wireless so I think it'll be perfect if you want it hidden. Although it's quite expensive. You might want to check the Canary cameras? It's a 1080 cam, less than a hundred $$. They look like a speaker at first glance. This might help
here. You wouldn't notice it's a cam unless you take a closer look, that's when you'll see the lens. I just feel its motion sensor will need a little update, unfortunately, it's too sensitive, you'd be receiving a lot of false notifs