As for now i think the low-cost fund solution with the slightly narrower index will be my best option.
Vanguard Total World (VT) holds about 10% emerging markets with a 0.08% expense ratio. Getting both emerging and developed markets ("all world") for a really low annual costs is great. What are you seeing for annual costs for the "all world" versus "world" funds/ETFs?
Another option is to split the investments up. For example:
Vanguard Total World (VT) charges 0.08% and is about 55% U.S. stocks / 45% rest of the world
Vanguard Total Stock (VTI) charges 0.03% and is 100% U.S. stocks
Vanguard Total International (VXUS) charges 0.08% and is 100% international stocks.
So roughly speaking, I can buy half VTI and half VXUS, and pay 0.055% per year... instead of buying VT and paying 0.08% per year on the whole thing. You could further split international into developed markets (VEA) and emerging markets (VWO), if you have those funds where you live. I don't mind the added complexity of 3 funds versus 1, so I might go with VTI / VEA / VWO ... splitting up U.S. , developed , and emerging markets.
But starting is more important than saving 0.10% in expense ratio. You can always sell the investment later and switch to something more efficient. But you can't go back in time and start investing earlier.