Tell me more about the iron bridge on Little River. I was unaware of that. There was at least one iron bridge at San Bois Creek -- this would have been Whipple's Route which I believe is the same as Beale's Wagon Road. I believe the bridge on Blue at Nail's was an iron bridge. I don't know about the others on the Butterfield/Overland Mail Route (Ft Smith to Boggy Depot to Sherman TX).
I'd be surprised if Phillips did not carry his dead back to Ft Gibson. If any were buried during the expedition, I wouldn't expect any kind of permanent marker though they may have covered the grave with rocks to keep animals from digging.
Ken