I went through this too. No one really helped me out other than telling me to take a sawzall to it.
Take the brackets all the way off and lift the front end up about 6-10 inches and drag the whole tank towards the bow. You might have to lift up on the back of the tank to clear the dump pump. Go all the way to the back of the seat. Then, lift up on the back of the tank and it will come right out. It took me about 2 hours to figure out how they come out but they came out the same for both of mone. I also have the team wedge tanks too.