rwehuman is right...the log approach works. I used to use it before I bought beach wheels. Its relatively cheap, easy to ready..but there are some issues. The biggest problem is...these pipes get VERY heavy as you go to larger diameters. That makes trailering and carrying them around an issue. You will also feel like you are a slave hauling rocks up to build the Egyptian pyramids...runnning pipes that come out the back an put them on the front again.
But if you want to pursue...
[list=]rwehuman is right, you need to make sure you have large diameter pipe, especially if the sand is at all soft - which it sounds like it is since you are concerned about getting a vehicle stuck. Mine was about 6 inches, but you will need to look at your beach. But watch out...these get heavy!
You will need at least 3 pipes. 2 won't work to keep it moving.
10 ft is a good length to give you plenty of clearance (its also a nice round number
This method works best if you aren't carrying it over a very large beach as its pretty labor intensive.
Overall, My suggestion is invest in the beach wheels or make a set your self. The "Logs" will work, but after getting a set of wheels myself...the logs sit under the deck now.