Yes, you can raise males (boars) and females (gilts) in the same pen. We keep males and females together. Our pigs become sexually active around four or five months but the females do not generally take (get pregnant) until eight months, rarely we'll see one take at six months. One generally slaughters them by six months so that is not a problem. If you want you could separate them around the fifth month. They do like being together and will likely grow faster together as they are competitive feeders - they see someone else eating and think of eating. Note that our
experience is with farm pigs. I don't know if the small pigs like Pot Bellied are the same.
I would suggest dividing your acre up into a minimum of four paddocks and then doing managed rotational grazing. That will improve the soil and forages over time. See:
http://www.google.com/search?q=site:sugarmtnfarm.com+managed%20rotational%20grazing
Cheers,
-Walter Jeffries
Sugar Mountain Farm
Pastured Pigs, Sheep & Kids
in the mountains of Vermont
http://SugarMtnFarm.com/