Predominantly Acorn-Based Diet for Kune Kune pigs?

Has anyone fed their Kune Kune pigs a primarily acorn diet? We have a huge amount of white oaks on our property and plan to rotate the pigs through the forest and supplement with minerals, then have them closer to the main pasture in winter in a semi-permanent run for the cold season. I'm considering going feedless, but haven't seen many examples. Even in Spring, we have endless acorns on the ground.

I feel that feeding the pigs a balance diet would be good because acorns contain tannin.

Tannin can cause digestive issues and even kidney or liver damage if consumed in large quantities.