Yeah I was afraid to go that low. I'm at 30 currently. Definitely comfortable but may go back up a little. My other vehicle is a Ram 3500 so even at 38-40psi the LX was very comfortable to me.I would have no qualms about using a SL tire. It's certainly no worse and possibly more robust than the OEM tire based on the load index. There's no safety here. Whether that will meet individual expectations or enthusiasts usage outside of stock parameters, is a separate question.
I would take RCTIP with a grain of salt. It's a good cross check and starting basis, but is not all encompassing. It does not for instance address handling and stability. Only that the tire carcass will not overheat given said load. 26PSI IMO is way low for a tall profile tire like that, that will risk sidewall rollover in a more dynamic handling maneuver. At worse, possibly even lose a bead. I would recommend 30-35PSI is a better ballpark.