I think the way this message is delivered needs to change. Of COURSE people need to stay at their own homes and not bugger all over the country, putting small communities at risk, but I understand the reasons why they do this, and it's only by tackling this will we actually succeed in stopping people from trying to travel.
From a city-dweller's point of view, all we see of fresh air is often the lovely pictures on twitter and FB of people going on their lovely country walks. Meanwhile city parks are being shut and even the government-allowed one walk a day is under pressure.
So, when people in rural tourist hotspots post messages saying "stay away, we don't want you here", it often reads as "I'm alright, Jack, and having lovely country walks, and you can fuck off, you disease-ridden urban scum". (Note: I KNOW THIS IS NOT WHAT IS MEANT, AND I AGREE WITH THE MESSAGE THAT TOURISTS SHOULD STAY AWAY. It's the way the message is phrased that needs changing, not the "stay away" content of the message.) I haven't read the whole thread, but there was a post here where someone complained that their dad wasn't getting his walk on the beach because of all those other bastards who were wanting to walk on the beach. You can see the communications problem...
And we are getting into nice weather, and we are looking at months of this. Of course people want to do the best for their own families, and they look at the lovely pics, and they sit in their flats, and they come to a completely terrible decision, and they climb into their caravans or whatever.
What we need are compare and contrast pics of the relevant medical centres, rural and urban. The messaging needs to change from "fuck off and let us have our paradise in peace without you pestilential city dwellers" to "if you come here you are in serious danger of not having any access to adequate medical care, because there simply isn't enough, and you will take others down with you, too". We really need to bang the drum that moving to the country for lockdown puts their families at more risk, not less. That, if/when it sinks in, is what will change behaviour.