i had similar problem to adeysolaris, i virtually done the same using sealer, i had major water problems in the boot. luckily it only took me a couple of days to sort out the boot part of my problem thanks to this site and a bit of luck. i done mine in parts, you could do all of this in a couple of hours properly if you have half a clue with cars. take both rear light cluster out and dry with hair dryer as much as you can. clean dirt off etc, take gaskets out clean and dry them as best you can. use sealant ( i used loctite from halfords 5 quid is perfect) on both sides of the gasket and after cleaning everything up on the car side as well screw them back into place. i also found by luck that the bit where you put the nozzle to fill petrol up was leaking water, i used a phone camera with the light on and happened to put it in the wing that you cant visibly see from inside the boot and i could see the line of water entering from under that part when i watched the video back. - i was very surprised this could leak, i would never have thought about it and it looks completely perfect from the outside. so i sealed it from the outside with sealer and also put sealer on the hatch to roof joins just in case. i read toyota relied on the paint to be the sealer of that part? (could see a very very fine hairline crack as a lot of people mention, on one side) this totally solved the leaking boot issues for me. i never read anywhere else online about the leak under the petrol filler so its definately worth a look at. the only other post i seen is above about the filler on the damaged wing, mine however, is not a damaged wing and its happened. now onto the leak in the drivers footwell for me. :-(