Pete, Trent, and Danny doing Quandary Canyon (San Rafael Swell) on 09May2020. Quandary boasts beautiful scenery and interesting obstacles including many keeper pots (which Pete did a lackluster job of recording).
Out of curiosity...had you not had the sand trap, were there other anchor options at the locations where you used the sand trap? My group doesn't have one, and the stores we've checked don't either right now.
Or, you could just leave the SandTrap for the last person to rappel off of, and pull the Trap when everybody is down. (Always several ways to do things. I'm a bit leary of rappelling off a single Pot Shot).
three-person SandTrap - not advisable. Four person minimum, really. Gotta test it good before the last person goes. Even when proficient with the Trap, not advisable.