Glad to hear your Kunes have settled-in Harry. Not sure if you've got castrates or entires - but I'd be careful mixing entires from different litters - Kunes mature sexually quite early compared to other breeds (about 5 months-old) & may scrap even with no females to wind 'em up
Your field sounds like Kune heaven - mine love nettles & docks, clover, goosegrass etc in preference to just grass. If you want them to dig it up you will probable need to confine them to small areas & move them around - are they trained to electric fencing? I use the white "horse tape" as they can see it easier. They will also be more likely to root if you throw their feed on the ground too.
Mine are also fine with chucks, ducks & turkey poults who frequent the paddock the mums & piglets are in (not stupid - they know the "maternity wing" gets the extras
They also ignore our daft Setters, who are more scared of the pigs than the other way round!
As a guide, we recently sent some to the abbatoir; a 14-month castrate killed-out at 82kgs, a 7-month boar killed-out at 24kgs & a year-old boar killed-out at 54kgs. No sign of any boar-taint, but we haven't tried Karen's sensitivity test yet