I had to replace the valve before and you are "supposed" to be able to do it through that access where the livewell pumps are but I couldn't had to pull the tank - can't be really easy so I just had the dealer do it - an hours labor.
If you run the tank as empty as you can it is real easy, but it does take two people to lift it out. I did it on mine and it made changing the valve super easy! I'm a big guy and there is no way I could change valve without pulling tank. Shop wanted 250 bucks to change valve, spent that money on something else, lol!