This is certainly a tricky one - I'd echo Paco's question.
Yes, there were certainly a few Saunders families in the area. For example, Benjamin and Betty were pretty fecund prior to their 1812 marriage in Mosterton - is their Robert b.1802/3 definitely too late for you? I can't see where Charles (Chedington 1841 census) comes from.
The church history in these parts is a bit complex. Chedington, South Perrott and Mosterton are quite close to each other and the relationships between them in terms of seniority has varied over the years. The OPC page for Chedington says there are no baptism records prior to 1813, though a church (somewhere in Chedington Court's grounds) certainly existed then. The new church, now redundant, was built in 1841. I've had a quick look through Mosterton and South Perrott records, but there's no sign of any Saunders marriages in the years just before 1797.