water in the boot

Hi

My fabia estate has a very strange case of letting rainwater into the boot.

I say strange because sometimes when its bucketing it down it only lets in a little water and other times with less rain I find there is more water!

I have taken out the boot sides to try and see where its coming from, and the only place it appears to be coming in is around the light cluster area.

I have sealed around the boot hinges which made no difference at all, no leaks from the washer and nothing much in the spare wheel well, so it must be the lights.

Does anyone have any tips about sealing the lights, I don't want to use silicone as I may need to take them out!

Thankyou