We share the same problem. There is no perfect solution, but here are some thoughts. As for my qualifications, I will say that I have pooped in a LOT of diapers.
There are two top priorities in a good diaper for fecal accidents:
#1 - The top priority is that the diaper
fits your personal anatomy very well. A diaper that does not fit well will leak regardless of how expensive it is. You want a good seal at the crotch. The leg elastics should be snug but not overly tight.
#2 - The second priority is that the diaper has very tall internal standing leak guards.
Look for standing leak guards that are at least 1.5" high. For example, BetterDry has leak guards that are a bit over 2" high. Others with very high leak guards are Megamax, Rearz Inspire InControl+ and Rearz Elite Hybrid. Any functional leak guard will help, but I would avoid a diaper with leak guards less than 1.0" high.
Next, look for elastic leg elastics that are functional, rather than just decorative. They are your last line of defense if poop leaks over the internal standing leak guards..
A plastic-backed diaper will do a better job of containing fecal odor.
The diaper should have "sag space" or a "fecal containment zone" in the rear. This essentially is a bit of extra space designed in a good diaper for poop. Note that, if you tighten the diaper too much you may flatten this space and reduce the space available for diarrhea or other fecal accidents.
The diaper does not need to be highly absorbent for bowel accidents. Poop, even diarrhea, will clog the mat in any diaper and slow or inhibit absorption.
You mentioned Gary PUL pants. They are great diaper covers and I also wear them. However, PUL material is breathable and transmits more fecal odor from a bowel accident. To reduce bowel odor, vinyl plastic or rubber pants work better. iMHO, rubber pants work the best but are a bit heavier and more expensive. At home, if I expect a bowel accident I will wear rubber pants.
--John
(double incontinent)