I have to admit that I'm 100% VTSAX. It seems good enough to me. Some international exposure through top US companies, no currency exchange issues (I'm in US), and I can buy one thing, which makes more likely to buy that one thing.
I continue to have on my task list to research asset allocation, but I haven't seen enough to make me motivated to switch. For me, there's a bigger risk of inaction through paralysis versus benefits of further diversification.
Of course, I'm not really in a position where I need to draw down on my stocks anytime soon, so maybe that's part of it.
In any event, carry on. I'm a big believer in behavioral errors, so I wonder how much cost there is resulting from people not taking action due to confusion over asset allocation, versus just telling them to buy one thing and there's a better chance that they'll do that.