There are a few awnings like the Alu Cab Shadow that are considered "free standing". They are very stout compared to the non free standing. I can actually do chin ups on the awning arms near the pivot point with no poles. (My awning is currently mounted to my trailer) I've noticed that there is a difference in stategy by different 270* awning manufacturerers. The ones that claim their awning to be free standing have a very stout pivot setup and thus require the rear mount to provide support so their awning will function as designed. Other 270* awnings that are not free standing use poles to support the awning taking the stress off the rear mount. One pole is provided for the Alu Cab for severe wind conditions, but it is considered a free standing awning. The Eezi-Awn Bat 270 that @Dirty Koala has, I believe, is not a free standing awning.
Correction: The Eezi-Awn Bat 270 is free standing.