The business class Global Explorer has a maximum mileage of 34,000 - your itinerary exceeds that by quite a bit
So you're looking at a 5 continent Oneworld Explorer (a DONE5)

I see one problem: there is no Oneworld airline flying between BKK and SGN
Perhaps another surface segment? Bus from Bangkok to Siem Reap, a couple of days having a Captain Cook at Angkor Wat, then a fast boat down to Phnom Penh, finally a bus to Ho Chi Minh City.

pye1201