Don't get further in debt just to get a guest room... cheaper to put guests up in a hotel unless you have them all the time.
My wife has started a professional organizing business in Houston by the way (have to plug it for her since Rhoni brought up this kinda stuff. lol. it is
http://www.organizationalbliss.com ... you would be surprised what you can do with your existing space. Are both offices used full time? If not put a day bed in the partially used office and add lots of shelves and containers for storage.