What about a radical solution, as Avebury is such an important prehistoric place perhaps the NT should buy up the houses of the village. Okay we are going back to a feudal structure, but Lacock village houses are owned by the NT and its integrity is assured by ownership within the nation as a whole - a common inheritance...
There are plans to build a new house just outside the henge but within the village, such things should not really be allowed on a long term basis, as accreting more buildings under the "right of private ownership" is harmful to Avebury as a World Heritage Site..
(Anyone who does'nt know Lacock, Wilts - its a pretty village full of historic houses),
In the end the car park vis the Pagans is a small problem in a much larger problem that needs to be addressed, as to the future protection of the Avebury stones and landscape....