Alimony Question

Does anyone one know if I can write in a sep. agreement that instead of alimony payments in “cash or check” I agree that I pay her rent and still be able to write these payments off on my taxes?
The long story is I agreed that she could have all equity in our house up until a certain month last year. With the economy the way it is, she still has no job and I let her stay for free while I make the mortgage payment. She signed a quit claim deed over to me last fall giving up her name on the deed. I could just write her a check every month and then have her cash it and give it right back to me to prove to the taxman, but would rather keep it simple.
I know this isn’t a forum for tax laws, but thought I’d give it a shot. Thanks

Edited to add: Also, from reading older posts I understand that alimony terms can’t be modified in a separation agreement, most post dealing with one party wanting a change. But what if both parties agree to the change? Can we modify it then?

I am by no means an expert, but my boyfriend had alimony to pay for 2 years, and his ex stayed in the house. She didn’t pay the mortgage for months, and he had to pay it so that the house wouldn’t foreclose. She, also, refused to get a job. His lawyer took her to court, and the judge changed the order and now he pays the mortgage and not his ex. And, she can only stay in the house until a certain date, then she must vacate and leave the house in the same order it was in on the date of court. At that point, she doesn’t receive anything other than her ED that she has already received.

You may structure alimony so that you are paying her rent directly, and so long as it is clearly spelled out that the rent payments are intended as alimony for your ex’s support.
You may modify any terms in a separation agreement so long as the new terms are in writing and signed by each of your in front of a notary public. The non modification simply means that neither of you can petition to change the alimony without the other’s consent.