Hello @Simon2362 & welcome to ABB CC from across the miles in Remuera, Auckland, New Zealand.
By the sounds of it you are home most of the time so will be there for your guests.
Maybe have several different places where you can place a key in the garden/ outdoor shed etc for your guests should you not be there when they return.
When talking to guests who you know may be returning when you are out, explain with the word " 'If" I'm not here there will be a key in xyz place please bring it inside when you arrive home & leave it on the table or wherever".
It covers your own circumstances without letting on to a guest that you may or may not be home & your routine.
Change the place where it's kept with each guest to help protect your property & personal belongings.
Your home is your castle & are treating your guests like family treat each other & their friends with an open door policy with a traditional knock on door to greet a person in your community, not just a money making venture.
I have a private room also in my home & have a general open chit chat to get a feel of guests, more so overnight/ couple of days stay, what their plans are to get an idea of what time they are coming & going.
Some are straight forward about their plans & say they don't & won't need a key.
Perhaps they have concerns about losing keys!
I advise where the key will be should I not be home & to bring the key inside & where to leave it.
If they are coming home later at night & should I be already in bed they know how they can get inside.
If you are in an area where it's safe & you are at home & know your guests are coming home later for whatever reason, before you go to bed you could always tell them you will leave a key under your front door mat, or pot plant, or leave the door slightly ajar and ask them to bring it in & obviously close the door when they get in.
Alternatively if it's a guest who perhaps is concerned about getting about safely and home safely there's nothing wrong with suggesting the guest send you a text when they are due home & to open the door when they arrive as one would their own family members.
Personal Safety is more important than some of those in the ABB community than some may realise particularly where people are traveling alone.
Longer term guests also know they are not to remove the keys off the property & so far I've had only one take it off premises.
Some things are common courtesy & respect.
When one has had property stolen or been a victim of crime one tends to naturally be more cautious about home security & one's personal property & safety in general.
Meanwhile, how about wording your listing in a manner to attract guests who share the same values as yourself if you haven't already?
One of my key points in my listing is Personal Safety- have a look.
There's plenty of options you can exercise.
It's unfortunate the days of having no locks on the door & leaving the door wide open when one goes out are well gone in society.
All the best