Yes, it always a crap shoot. I have been where the entire run was hard pack and a Camry could have gone down and back and then I have been times where I was worried we wouldn't have the fuel to return because the sand was so deep and soft we were getting 4-6 mpg's trugging along.
Keep your GMRS radio with you and tuned to the NOAA channel. For the most part you should have a pretty good idea of what to expect within the following 72 hours. Tides are relatively low for the most part, moving 1.3-1.7 feet at most. I've never had a run in with anyone in all of my years running PINS or even lately doing the Matagorda run but rest assured that I always take along a fix or two for those "what if" moments.
A few of us will be there Nov. 30 through Dec. 2, feel free to tag along. Like @perterra said, it's not really worth the trip if you don't overnight at least for one night.
I always carry extra fuel. My rig doesn’t get good fuel mileage on city streets let alone off pavement. Soft sand really eats up fuel. But that’s all part of the planing. It’s a long way down and then back. Everything can change in a hurry. Extra food water fuel. Never hurts to have extra. Weather can be checked before you head out. So can high and low tide times. But as said weather can affect the tides. In all reality I have never had a problem, beach wise. But you have to remain alert. Things change with tides and the beach can get skinny’s day/or soft. In the Summer seaweed can hide hazzards. Can’t wait till next week to get back down there. Always an adventure it seem and that’s why I travel.