I have had in the past the results of mating white boars onto native females but the offsprings are small when grown out.When mules or jackasses are produce,mating of male donkey onto horse mares the end result is large mules/jackass but sterile.I have seen ramps built for the donkey so he can reach the heated mares with success.You are right Doc,able to reach is going to be a problem but with a ramp this should be okay.There seems to be a move in country today for more natural livestocks and some people are doing very well with poultry like the 45 day chicken grown out to over 60 days and better tasting meat.
There is a breed of hog in the west, the American black hog that is a pasture hog,am hoping that a native male crossed onto white females might produce something similar and the dark pigment would allow for outside living.Just an idea I am working on.On the other hand,might be more over a fantasy over realism.
Michael