After having new sheet metal welded in and checking and double checking my drains I thought I was good to go so I installed sound-proofing panels and reinstalled my carpet, etc...
Only to discover I STILL had water coming into the driver's footwell. Guess what? Sure, my hood-hinge drain was working OK, it was splitting the stream of water between the wheelwell and the footwell! I careully removed as much rusty metal as I could and started by patching from the inside with fiberglass cloth and fiberglass dope. The new patch is just south of the hood release cable grommet and extends all the way to the right and bumps up against the parking brake anchor. Then I tucked it into the seam really well and brought it back towards me on the left, underneath the footwell side panel.
Then I got in the wheel well and did the same from the outside. I had to tear everything out because I failed to extend the patch up high enough to where the leak was but it looks like the 2nd time I've finally got it: pouring water on the hood so that it streams down and into the drain does NOT introduce water into the footwell anymore.

As for the SLS: after replacing the accumulators I can tell you:
1. NO MORE BOUNCING!!!
2. Rear end does not sag as low as it did before when the car sat overnight.
3. Rear end IMMEDIATELY comes up to level when car is started. It does not have to idle for a few minutes.
4. I definitely feel and hear bumps now from the back end, but getting rid of the bouncing is worth it!