To park safely in Merthyr, I just bought an old Honda CX 500 !
You could park that anywhere and leave the keys in it!
It was always there when I came back. Once someone had actually left me a fiver on the seat....... Out of sympathy....
All you've got to do is buy a scabby bike but always park it next to a tidy one.
They'll always nick the tidy one and leave your scabby beast alone.
So next time you park your tidy bike anywhere, take a look! If there is a scabby CX 500 parked next to you...... Then it's yours that's going to get nicked!!!!
Cheers.