My '97 GS-R hatchback also had leaky taillights (water in spare tire well), which I fixed for free if you don't count the cost of the RTV silicone caulk tube I already owned. I just took the lights out, and reinstalled with the old gaskets and a lot of goop. Part of the problem is that with the car pointed uphill, water that drains around the hatch accumulates along the top of the light assemblies, underneath the black plastic ramp fairing that forms the top of the taillights that you see exposed when the hatch is open. In the underneath part, there are a number of plastic-casting reinforcement webs, and they form dikes and make a series of puddles which only drain away when the car is pointed nose-downhill. The puddles constantly are in contact with the foam rubber taillight / body gasket, and after a while they inevitably leak. In my car, there were obvious "bathtub rings" of algae where the puddles lay. Along with my RTV fix, I also drilled some small drain holes in the plastic webs, to allow water to drain downwards towards the sides of the car. This will be much more obvious to you when you unbolt the taillight housings from the body. This fix has worked perfectly for several years now, parking always outside in Seattle. PS -- the other way the taillights can leak, right into the lightbulb/reflectior assembly, is also common on Hondas here. I've had perfectly good luck drilling the smallest possible hole (1/16th" for my set) right through the face of the lens at the low spot. The hole is too small to see, or to cause problems with water coming in.