A couple questions.
First of all, it looks like that's a strap with hooks. If it is, it's a static strap and should only be used for a static pull (where you slowly proceed forward until the strap is taught, then apply power). You are much more limited when on soil with a low shear strength, such as sand.
I'd highly recommend getting rid of any strap with hooks, and replacing it with a good dynamic strap. If you haven't read
TVOR's vehicle recovery article, I'd also urge you to do that.
Also, were you wrapping your bumper support bar with the strap? It could easily get damaged by the sharp corners of the sheet metal. Also, watch for the airbag sensor back there, don't want to accidentally deploy that.
Next time, bring a small tree strap, and hook to both of your front tow hooks. It provides a very strong point to pull from. Shown below.
None-the-less, glad you made it out.