I don’t have a pitch marker but always leave a few bits ‘n pieces about to mark our territory. Couple of years ago was staying at a site here in Ireland - lovely big site where we had been allocated a space with a number spray painted on the tarmac pitch. Went out for the day(to visit Father Ted’s house!) & left 3 bikes at the end of the tarmac pitch, an electrical cable alongside the pitch & a fold up table on the pitch. Came back that evening to find a large white camper on our pitch, neatly parked amongst our belongings, with a drive away awning erected. They had a world of belongings exploded across the pitch! I spoke to the (very apologetic) campsite owner, who offered to move them - it would have taken hours to pack them up so I decided to be the bigger person, and suggested I move my small convenient California to another empty pitch. We ended up on a pitch behind them. When I went to retrieve my belongings from the original pitch, the owner came out and nicely told me to take my time moving my belongings - there was no rush! My kids were less than impressed! They suggested over the week, that as the great white had a constantly open ‘sun roof’ / hatch, and there were hundreds of sea gulls around, it would have been interesting to throw pieces of food up onto the roof of the great white / in their sun roof over the week!
In over 40 years of camping I’ve not needed a pitch marker before this! Watching this thread for ideas