I Had the rust by the lights and the latch also. The latch was so rusty I had to remove it and derust it with phosphoric acid. I also used the acid to remove the rust around the light holes, inside and out. First, grind the rust and paint off around the rusty areas then apply phosphoric acid with a Q-Tip and a swab (like those in a PVC cement cap with the wire handle) to get the insides areas - bend the handle as needed, and keep applying until all the rust is gone. The acid will NOT hurt the raw steel, it just eats the rust. Then remove the residue with alcohol and you are ready to repaint. I got the paint from an auto paint supply store. They mixed it and put it in a spray can and it worked great.
Mine had ablolutely NO signs of any water leaks inside the hatch. I believe it is from outside water getting blown up from air turbulance at the rear of the vehicle while driving. The stupid gaskets they used for the lights and the latch handle are FOAM so they hold the water. Get rid of them and make rubber ones out of old bike tubes.
About 2 days of work, total,
Good luck!
cp