Having tried several alternatives we have reached the conclusion that degenerated granite (known as DG in the trade) is the best surface outside the alpaca barn.
It goes down almost like sand but given some rain, a little compacting and sunshine it bakes hard. This makes it an excellent surface to scoop alpaca poop from. Unlike say 3/4 minus where every scoop of alpaca poop contains a pound of 3/4 minus !
So today was the day to resurface the area outside the barn with DG.
The barn is 60 feet long and 30 feet wide so I needed a run about 20 feet wide and 150 feet long. I ordered 25 cubic yards which did the job just fine with some left over for other projects....
Adrian Stewart