Many of the properties on the estate I live on have similar 'private' parking areas. Some people simply paint their house number on the road (or place a numbered sign on the verge by their parking space). However, in some parking areas, somebody has obviously taken on the job of systematically labelling the parking places.
So, if you want an 'individual' approach, you could simply find a way to label your own space. However, to gain the approval of your neighbours (who may be experiencing similar problems to your own) why not consider taking on the task of labelling all of the spaces around your own parking bay?
I suggest putting a standard letter through your neighbours' letterboxes along the lines of the following:
"Dear neighbour,
As you're probably aware, each property in this area has its own allocated parking area, defined in the deeds to the property. Also, as you're also doubtless aware, there are sometimes problems with finding a parking space. It's my intention to label my own space by painting the house number on the road but I'd also be happy to label your parking space, in a similar manner, if you'd be kind enough to let me know which bay is allocated to your property. I look forward to hearing from you, in the hope that we can work together to solve the current parking problems'.
Such a letter offers nothing other than cordiality and cooperation but, at the same time, it makes it clear that you're determined to retain your right to park in your own 'private' space.
Chris