How to Prove Future BAH when renting an appartment.

Im in the army, I've been in for 2 years. I got married back in March and have been waiting to put in for my BAH untill July for the Backpay to be able to buy basic furniture and the deposit. The apartment that I want to rent, is saying I should put in my application now to reserve the place until July. My question is how do I prove to them that I will be getting said BAH when I submit the application? I want to reserve the place because it's cheap, in a good area and super close to base. I saw another thread from a year ago, but the guy was an officer going into the military, so it wasn't a whole lot of help. Any help would be appreciated!