Yeah there are various workarounds that function to one degree or another, but none are ideal, mostly because they require constant user input. So once you're AFK for a brief period of time (pee break, getting food/drink, partner/pet aggro, or just waiting for a team to form) you're going to lose your buffs. Which isn't terrible for PBs, but really sucks for a Dom.
I could probably write an AutoHotKey script that would get the job done, but again, not an ideal nor elegant solution.