I agree that 5 or 6" of dynamic travel is enough for normal roads (and said so above). The problem is that static height changes with load. On my F350 dually 5.4" from empty to laden at the rear axle, according to the Ford bodybuilders book (and my practical experience). That is pretty much the whole travel of your bag right there before dynamic suspension movement is considered. Set for middle of travel laden, they will be overextended empty; set for empty they will be smashed flat when only half laden. You can really only position them right for one load condition - unless they are allowed to float free on extension, like the Daystar product allows. Of course 100 PSI in them will lessen the compression when laden, but not that much.
Put your truck on a frame rack to change tires or oil, you will be at full droop both sides, hanging from the bags. Firestone says not to do that, then realizing that you have to, says its OK in an emergency as long as you deflate them completely.
