Ashley, you don't state what year yours is but here is a sales link to the same model trailer you have:
You have a rear bath, mid kitchen unit from what it says. At the 5:21 mark you see the main dump at the rear for your black and gray tanks. Now, at the 4:37 mark while he is talking about seals and sort of pointing back toward the tires, look up at what appears to be right above the front tire; I believe it will be between the 2 tires. There is a little silver bar in the pic. If you look closely it looks like you can see where it goes through the frame. I believe that will be the pull handle for your galley grey tank.