Your timing is just a little off.
Could you tell us where you found the leak in the shower pan, and how you determined that was where to look? Apparently for years, my E38 has had water under the bow drawers and there is quite a bit of damage to the shower bulkhead, the bottom drawer cutout, and the adjacent angled bulkhead further to starboard. I am just noticing that there is discoloration to the bow floorboard and the "vanity" seat vertical piece. After I eliminate the problem, I will fix the last four damaged areas.
It took me almost two years to get down to serious troubleshooting - taking things apart. It's the bow water tank, obviously. Obviously.
The PO had the bow water tank pressure tested. I could never determine for sure that the outlet fitting wasn't leaking. I couldn't feel any moisture there. I resisted the very reasonable suggestion that I put food coloring dye in the water - just stubbornness.
A few weeks ago I removed the tank and confirmed it is sound. The 1/2" gray plastic outlet elbow was installed backwards, and there was a lot of rust caked around it where it went into the tank. So I am still suspicious of that. One side is pipe thread and the other is straight thread, but it is very hard to tell which is which. Try it both ways and you'll see the difference. Properly installed, with the pipe thread into the tank fitting, there is no leak there.
We did one overnight with the tank out (used the shower!), and found a little water a few days later when I thought to check. Unfortunately, I had not closed the gray plastic ship's supply line, so I still haven't ruled out that source for this last incident. I've found no evidence of deck leaks or from further forward. I've checked under the head sink - nothing wet. And it was fresh water.
This past weekend (really) it occurred to me that the shower drain could be the source of the water, but I haven't taken it apart since I'm working to put things back together for the rendezvous this coming weekend. The bulkhead sealing job looks relatively new, but that is meaningless. Maybe I'll look at the drain itself tomorrow night.