Yeah I've been fighting with it off and on for a couple of days. Today I thought I was getting somewhere with the tank loosened up, but it turns out all I'm doing is shoving the tank downward because it's loose.
The later design that goes through the outside of the quarter is the way to do it, if you don't mind the stupid looking fitment of the cap.
FWIW I've lubed it with motor oil, then read somewhere to not do that because it degrades the rubber and to use ATF instead. OK, that doesn't work either. Today I gave it a couple of healthy shots of silicone spray lube, still no improvement.
Heading back out to fight it some more now. Man I love working on cars /s
At least it's a new tank, so there was no siphoning involved and I'm not sloshing gas in my eyes etc.
ETA - if you don't make sure you've got it lined up with the grommet, you'll bend the tongue that sticks out of the end of the filler when you twist and turn the filler. DAMHIK.
ETA2 - if you bend the tongue you probably cut the grommet and will need another one