We transited in 2010. Our experience: anchor
the day before in front of the bridge, then take the dinghy
in with a depth sounder
. We used a very high-tech solution: a dinghy
oar with a tape that showed our draft
. It was very helpful as we mapped out the actual channel (it meanders).
We always had plenty of water
under our keel
(4'9''), but without the mapping beforehand we would've grounded at least once.
There is a small white red-ish buoy in the middle of mangroves transit - it marks a wreck that almost shows, so be careful around it in the dinghy.
We found the buoys on the other side slightly confusing, but maybe because we had to be up for the bridge opening at 4:30 am (don't remember for sure about the time).