Ha ha, Isn't that just a mongrel of a job!!!!, It just about drove me to drink when I took mine off! I think from memory there is only the 3 nuts but to get it off the flap has to be sort of half open (which is real hard because of the spring and the fact it's unbolted) I suggest walking away from it for 30 mins, go and have several stiff drinks and have another go
(lots of masking tape around and on the flap will help to stop scratching of paint)
GOOD LUCK!!!!