I did the trail two weeks ago in my stock FJ Cruiser. It did the water crossing fine, water depth was 30". Like others have said, it does vary. And we just had two storms roll through, the most recent was also the largest on Thursday/Friday. It was my first time as well. I would caution against staying too far to the left, a guy before us did that and he couldn't keep momentum, it was so heavily pitted he was bouncing like a he was in a washing machine.
I went just left of center and it was smooth sailing. Like others have said, it's your call, and do get in over your head. Remember you need to drive that home. A snorkel isn't really going to help either, you'll fry electronics long before you start pulling water into your air intake. IMO. There's a catch basin and drain hole under your air filter. I have a video of me doing the crossing two weeks ago, I'll try to post it on youtube so I can share it. My only mistake was coming in too fast. So the splash did go over the hood, but it was just the splash, I wasn't submerged.
Do you know how to ride behind the wave? When you enter you'll create a wave and there will be a significant dip in water height behind that wave. You want to stay in that zone riding just behind the wave. That will keep your engine bay in lower water than the back half of your vehicle. My FJ had factory front diff and trans breathers so I only had to add a rear. Definitely, find out, and extend those diff breathers if you think you will do the crossing. You don't want the rapid change in diff pressure due to fast cooling to suck in water to your diff.
Most of all have fun, it was an amazing trip and the water crossing is literally that last 100 yards of trail. So don't focus too much on it. There is a ton of adventure the other 140+ miles.
