Adopted pogs and new cage building!

Hi! I have adopted some little girls (I think they are about a year old) from someone who was selling them on a Facebook buy and sell page, as their son had lost interest. Sigh. Anyway, I snapped them up and have been keeping their (far too small) cage open so they can wander about the corner alcove of the kitchen until we have done their new house. So the space we have to house their new home is quite long...2.25 m. I intend to have a double decker, or possibly a biggish loft bed/space for each pig at either end. So my question is (and bear in mind our house is not spacious so although i don't want the minimum space for them, we don't have the luxury of loads of space) ... How wide would it need to be for them to be happy? They will also have a nice spacious outdoor run where they can nibble the lawn on dry days. Thanks. Fwweeeep!