Hi Mike,
Theres plenty of room for a 3rd B/R, I'd prolly put it there, with the pillar as a corner-
Thus leaving an L shaped living area, as opposed to the 'T' large shape now. Easy to put a bathroom in too.
You could also go here, leaving a rectangular living area, but it would seperate the 3rd B/R, & plumbing more pricey-
Good luck- if you want to make the long haul & check out our place, you're welcome. Just tell Orr, and she'll fix it up with the MIL.