Your current itinerary may look like the following:
BKK-HKG-SFO (stopover North America 1) with CX
SFO-MEX on MX (stopover North America 2)
MEX-LIM on MX or LP (stopover South America 1)
SCL-AKL on LA (stopover SWP 1)
CHC-SYD on QF (stopover SWP 2)
CNS-SYD-BKK on QF/BA

Rewritten in another form: BKK-xHKG-oSFO-oMEX-LIM//SCL-AKL//CHC-SYD//CNS-xSYD-BKK; total segments (incl. land) 11 (which is ok, up to 16 allowed); stopovers would also be ok. Total mileage is around 28'900 miles which is very close to the max. of 29'000 (the issuing airline will need to confirm that you are under the 29K limit).

For the Circle Pacific product, flying a given segment or going overland makes absolutely no difference. The miles must be counted. So flying from SYD to BKK at the end or going overland means that the miles for SYD-BKK must be counted. Of course going overland from CNS to BKK would save you the miles for backtracking CNS-SYD. But since you need to buy a 29k-mile ticket anyway, it won't change your final price.

Fare is today THB 126'260 which equals GBP 2'545. Taxes are on top.

PS: I don't know whether an intercontinental surface segment is allowed at all