the only worse than a guest who gets refunded for leaving is a guest who gets refunded AFTER staying.
This sounds like a guest that very early on would have gotten this message from me: It seems like you're unhappy here, would you like to stay or would you like to go?
How can they ask for a refund after staying if you've gotten on record that despite everything they are choosing to stay??
With a guest like this, I would be on record (within the message thread) repeating every one of their complaints and either how you have addressed it or how you had already mentioned it in your listing.
I'm sorry the breaker has tripped, as I told you earlier, when you turn on the kettle you must turn off xy&z. The electrical panel is meant to run one heavy load item at a time. Please follow this instruction tomorrow when you make tea.
I'm sorry that you find the country to have too many bees, they are good for pollination & we're glad they're here. Here is an article about bee habitats...
I'm sorry you've not found enough shade for the children, we particularly enjoy (the park, the big tree out back, whatever...)
I'm sorry that you found mouse droppings, I've thoroughly cleaned the entire kitchen area, as I mentioned to you in a country space like this it is vitally important that you put away - in closed containers - all food items, dispose of rubbish in the closed top bins, and always wipe up spills and crumbs. If you follow these instructions the nature should not have a reason to follow you into the trailer.
A unique space requires some unique strategies, since many people will be ill equipped to go with the reality. Being proactive is your best move. Good luck