If you look at the beginning of this thread it shows silicone being used in the same place as your tape, between the bumper and the body. I didnt think this was where mine was leaking as the water was pooling under the vent, not the other side of the lip.
But today i undid the two screws on top of the bumper and pulled down on it. I found a hole right on the corner of the body, where the bumper raps around, so i have filled this with sealent and also put some where you have the tape.
I was not going to let this beat me but noticed today that i am now getting water on the other side, this looks like its coming from the vent though.
So i think it can get in from various place:
Through the screws that hold the lights in place
Through the vents
Through the top of the bumper
Through little holes in the bodywork
I think i might just take the bumper off, and use fibre glass to patch any holes, remove the vents and fibre glass the holes left and then silicone every join i can find. I will also remove the roof trim and reseal that.
If it still leaks after that i will just drill some holes in the corner of each side of the boot and let the water drain away,