Since I bought my Traveller in 2014 it's leaked water into the rear driver's footwell. Since then I've tried seemly everything to stop it. Sealing the roof seam, sealing all around the b post and centre rail capping, sealing all the seams around the floor. None of this has worked.
The wood has now been completely replaced, the car resprayed and all new seals fitted with sealant everywhere it's supposed to be. It still leaks water! It fills up whenever it rains and the floor is soaked and rapidly rusting.
I noticed today that the front drain hole in the centre rail wasn't draining any water so I drilled an additional hole in the runner to 'link up' with it. Pouring water in the runner showed that it was working. However, with the windows shut and testing with a hosepipe, I still have exactly the same problem. From the outside, it all looks tight and sealed but clearly there must be a problem.
The passenger side is absolutely bone dry. I can't see any difference in how things are arranged on either side so I just don't understand how one side is fine and the other leaks hugely.
I've spent eight years trying to solve this problem with no success and I'm now getting to the stage where I'm thinking of selling the car so that it doesn't rust to pieces. I've spent so many thousands of pounds over the years having the chassis, wood and various bodywork repaired but this one water leak seems to evade all efforts.
If anyone has any suggestions on things to check I would greatly appreciate it. It's driving me absolutely insane

Thanks,
James