This may not work for yours, but it did cure (at least for the time being) both a tailgate rattle and hatch squeak on my '02 LSE.
I found the rattle originated from the hatch struts. I tested this by jamming some soft foam / sponges around the well where the stusts lay when the hatch is closed. After driving a day or two, I noticed the rattle disappeared. Not wanting to drive with foam stuck in the hatch, I thought lubing up the struts might help. I lubed the connecting joints with WD-40 and that did it.
For the squeak, I dressed the glatch hatch weather strip with silicone. Next, I wiped the inside of the glass hatch with silicone as well. Note: just wipe the 'blackout' area of the glass, not the whole glass panel. This is the area of the glass that rests on the weather strip when closed. Me thinks the rubber weather strip on the glass blackout coating made the squeak. Something like tennis shoes on a varnished floor.
It worked for me, for 4 months now. We''ll see how long it lasts, but easy to repeat if needed.
Another rattle I cured was the headrest posts in the seats. Some soft foam in the holes cured that as well.
It may be a truck, but I too try to keep the rattles and squeaks minimal.
Good Luck!