You had a problem during the day, but your concerned about night time access. Which don't get me wrong, you should be, but i would address day security first.
Get an alarm, also get 1 or 2 surveillance cameras up, it would be awesome if you had this guys picture.
Maybe a game trail cam. $100 for a good one.
If you have a hidden house key, it better be as far as possible from the door, other side of the house at least. Your right, that is what he was looking for.
If your wife is home during the day and your not, that's the scary part..she should have quick access, there are various safes to accomplice this.
I'm sure you'll find something quickly if you search around the internet a bit.
I think the most f'd up incidences happen when a burglar breaks in, thinks there alone, suddenly bumps into a housewife and ends up doing something horrible, we wont get into it, im sure you seen a few stories on the news.
Put up a beware of dog sign, If you have a garage your wife parks in during the day, move her car outside during the day so it is seen.
It's inconvenient and a pain but if they see a car they'll try a easier house that doesn't have a car in it 99% of the time.
I recently put up a driveway alarm, best thing ive bought in awhile. Love this thing.
You dont have to knock on my door, ive already heard you coming 400 feet ago, im at the door watching you walk up waiting to greet you, or trying to stuff the dead hooker back under the mattress.
No surprises.
Ive got 3 sensors on it, front entrance of the driveway, half way down the driveway, just in case the first one misses you (which is rare) and back of the house. Different beeps so i know where you are just by listening.
https://www.amazon.com/Chamberlain-Wireless-Motion-Security-CWA2000/dp/B002ISVJL6