Not speaking from experience but I'd look around the internet for ways to clean it out in place if at all possible. Hopefully you have an access port and can get the fuel line off ( which ain't easy), jack the front up as far as possible and use a gas safe pump to get it out, rinse and repeat until perfectly clean. The pros use filters to pull out the water and sediment and recirculate until clean. I say this because it's going to be a good bit of work to cut out the deck, get the tank out, and then repair the deck and carpet. During my restore the tank was so wedged in that I had to cut the forward bulkhead out so I could get a big pry bar under the tank and work it loose, so just having a hole big enough to get the tank through might not be enough. You never know what problems or surprises are lurking below. I'm sure there are ways to clean that tank out without removing it, just don't know what they are. Hopefully someone can help out.