Just to conclude...
First of all, the previously discussed page in RAVE is not accurate for a THOR engine. There are some joints that can be accessed - way up out of the way, just in front of the fuel tank, but not shown in RAVE that I could find. The problem is, the fuel pump doesn't seem to pump continuously (on the key)unless the engine is cranking / running, so this is of no use whatsoever for a full tank of fuel.
The solution:
In the end I decided I had to try siphoning the fuel out.
The car does have an anti-siphon device fitted, but it isn't that good! A hosepipe is waaaay too big, and a 10mm (approx.) pipe was also too big, but I managed to get a very thin pipe down into the tank - probably approx 5-6mm external diameter, and cut to a point at the end. It took a while to get it going, and it took a long time to do, but it did work - very well. My tank was very full, which may have helped me, but I do have some more to drain when I have an empty container, so I will post back if I struggle next time (tank now less than half full).
I did use the pit. I lived to tell the tale. (I was careful!)
Many thanks to all for your suggestions and input.