I had to remove the tank on my '99 +8 a couple of times due to a leak.....
Gomog suggests that you can remove the boards by unbolting and rotating them. I found that the diff couldn't be raised enough to permit this. I ended cutting them out and fitting a piece of 18mm wbp ply which is wide enough to be removed after slipping back to clear the rear box section. (approx. 50mm wider than he gap between the chassis rails. Hold the tank with a couple of ratchet straps over the rear bulkhead. With practice I can now remove and refit in about 60 mins.
Yup, I followed exactly this process - except that on my first attempt I made the mistake of using 1/2" WBP, which isn't strong enough and bent after a few months, so I went back to proper wood.
