I highly recommend you to visit your spouse or even apply for a TRV. I'm going to see my wife in 8 days. We sent our outland spousal application in April 2016 with the checklist included, all forms filled out and signed by both me and my wife. It's been 8 months, and still we did not hear any news from our VO or even requesting additional docs if they ever needed them. So, I decided to visit my wife again. I was there last march (2016), and im going back again. We will be spending the month of December together. Im so happy! When I come back, I will send them passport stamps, hotel receipts, pictures of us, and other activity receipts. I'll order my notes when i come back, GOD I hope to see a "passed" for our eligibility. Im not sure what more i can do to prove our marriage is genuine.
Again if you can, go and visit your spouse. It helps. In fact, they may even waive the interview.