I'm trying to change the gasket on the part of the taillight that goes
up with the trunk. The driver's side one leaks water into the trunk
after a rain. I open the trunk and water pours in from the light
assembly.

I got a replacement gasket, supposedly for that assembly, but I can't
get the part off. There seem to be four bolts inside the trunk that
hold it on, but removing those only loosens it, it seems like there is
a fifth bolt. I think I feel it, but it's blocked by the trunk metal
and I can't figure out how to get it off. I don't even think an offset
nut driver would get at that part.

Anyone know how to do this?