I had my left rear fender liner out today. The factory application of seam sealer is very sloppy. I wondered about that forward seam that you have outlined. Can that forward seam be sealed from the cab side?Currently have my rear seat removed and the carpet folded back to expose the bare floor across that entire seat frame riser. Then water tested only the unsealed forward seam with the hose pointed only at the seam. Bingo, it leaks. Then repeated the hose in the bed and let gravity work to drain out the forward drains. Holy cow what a flood inside. This time on both sides of the cab, entering the cab entirely from the drain slots along the bottom of the seat frame riser, and it was all I could do to catch the water with a bath towel at the rate it was infiltrating. I'm also gaining a sense that Honda knows all about this leakage because they placed a foam blocker seal about 3" inside the ends of that seat riser. That blocker diverts any water into the carpet foam and keeps it from flowing out the ends of the riser toward the door sills.
I'm going to let my truck dry out while trying to figure out how to gain access to that seam without dropping the fuel tank. Thinking maybe working through the fuel pump access panel, but that's working blind and not much room to work.
After getting this deep into the problem, I'm convinced there are 2 types of Ridgelines... The ones that are known to leak, and the ones where it hasn't been noticed yet. This is a shame.