Electric trailer brakes?

They're available in both drum and disc models.

Even so, I don't think they'd regulate down for smooth driving like the hydraulic brakes do.

Why re-engineer the wheel?
Plus spend a lot of extra money?

Adapt some good auto brakes to your project and spend the money on more important things.

Keep in mind servicability in the field.
Not every town has a trailer supply house nor do most of them carry the parts you may need.