I wholeheartedly agree with Tom's recommendations. A few other thoughts:

When you are on a hill, be sure to face uphill when doing your job. That lets gravity work for you. Otherwise gravity can make things a lot messier.

I have also found it helpful to buckle the belt after lowering the pants. That not only controls the belt with all that it might carry, but it also seems to tighten pants which can otherwise bulge out in back at inopportune times. Incidentally, you may want to empty unsecured pockets, especially of heavy items into some container that can be closed, or even into a hat.

For one final general bathroom proceedure, which I doubt applies to PC2K's situation, never leave a handgun in or on a pair of pants which are being lowered. Find a more secure spot for it. When circumstances warrant, a handgun in a very secure holster on a belt can be temporarily left in the holster with the buckled belt looped over the neck and resting on one shoulder. The gun then hangs in as if an improvised shoulder holster under the opposite arm. I discovered that approach on a hunting trip in an area with a fairly aggressive mountain lion population.

John