I cannot help you on how to get the tank out as I have not seen your floor plan enough to know.
But I will pass this on which may help.
The large fill pipe, now a days the green and white ribbed one. That ribbed pipe can be a bugger to get it to seal back up. Even with double clamps you cannot seem to get even pressure all the way around to seal it up. On mine Sunline used FDA food rated silicone. This is not ordinary silicone it has to be special to not have any harmful additives to it. You can find this is Lowes or Home Depot I cannot remember which one. It is Aquarium silicone. Looks like this
Fish have the same concerns as us humans do. If you have a commercial outlet you can buy food rated silicone as well as we use it at work. But on the private sector Lowes and Home Depot seems to be the method.
The silicone is a double edge sword. Yes it fills in the spaces but it is so slippery that the hose will fly off until it cures. Best is if you are going to try this is to caulk, slide hose on and let it cure overnight to firm up. Then next day add 1 or 2 clamps.
If mine ever starts acting up again with that hose, the ribbed hose will be gone. I have read others getting ride of it too and going to a smooth bore hose. Costs a little more but it solves the problem without the silicone.
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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