Since you're talking about something short term (A year, give or take I guess) why not just rent office space? Rent paid for office space would probable be the same as or cheaper than a mortgage payment. The rent paid would be a fully deductible business expense to, along with all the utility costs. Also, you don't have to deal with depreciation at all on that rented space. You'd only depreciate any business assets you put in that space, such as furniture. I would guess that all you'd be putting in a rented space would be the same stuff you have in your home office right now, that you may or may not already be depreciating. So nothing would change when you relocated those assets to a rented space.
Now I don't know where you're physically located, but in my locale in NE Florida one can rent a 24 X 12 foot space in a strip mall for around $1400/mo plus utilities. It's also possible that there may be another business not related to your line of work that is renting space for their own business, and they may be willing to sub-let an unused room to you. I've seen this in a few doctor's and dentist's offices where they're not using one or more of the operatory/patient rooms and they rent out that one room to a programmer who only needs a small space anyway, for a table, one or two computers, telephone and other small tidbits. Generally, they will go for significantly less than renting a space in a strip mall for example.
