I haven't used either of these, but I came across them when researching flush outlets. - Trufig - DesignMod LLC

As Alex says, design the island body better to incorporate the needed outlets there. I’ve frequently used a 9” tray base cabinet at the end of a run with a false drawer at the top that contains the outlet. There are lots of other options as well, that do not require custom cabinets to make work.

I too would try very hard to not interrupt my beautiful waterfall with an outlet... in addition to the ideas above, could you do something like;

You can't use any outlet flush because they have nice rounded edges. I assume the flush one has square edges so you get a smaller gap.

Anyway, the other solutions are probably better.

Trufig.com