You are right.
Every option will lead to overweighting something and underweighting something else
That’s why it’s important to define when you underweight US, what exactly do you overweight
I think based on your answer, it seems following works best for you
World ETF + EXUS + XMME
There is no withholding tax advantage for VXUS vs IE based ex-US funds. You can also go for VXUS if you prefer that.
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Estate taxes is a complicated topic, there is a thread on this forum about it. It has a lot of comments. I recommend you to read it in full.