I think both work. The average reader doesn't need to conceptualize these distances. They just need to know they're reallllly far away and realllllllly realllll

I think both work. The average reader doesn't need to conceptualize these distances. They just need to know they're reallllly far away and realllllllly realllllllly (9x) far away. You can use the earth or pluto distances as relative scales.