You can do surface sectors.
One method of avoiding the two extra segments is to buy a cheap one way BKK-SGN or BKK-Hanoi-SGN. So for the RTW BKK-SGN would be surface.
You then have only 15 segments and you could add a few more flights - Alaska or Puerto Rico in the US.
You could also do HKG-FRA, then buy an inexpensive Spanair ticket to MAD - which leaves you two sectors for Dubai.