I've fished solo most of my fly fishing career, excluding all of the floating of the Sky and OP rivers, plus the Yakima of course. I carry the 10 essentials, plus cigars and whiskey, with at least 2 cigar lighters! A pdf is always with me now, and a small first aid kit in the car, that i will carry with me when I get a bigger waterproof sling pack!
I do now, at 59, prefer to fish with at least one other person when timing works out. I have balance issues and some health issues that make it preferable. When I am alone, i don't wade aggressively, usually keep it no higher than my knees and always have a wading staff with me. I may get an Inreach device so that if i do go off grid I can reach someone. I use an android phone, so am not sure about the satellite capabilities of it compared to the iPhone. Might be a reason to switch, but I prefer not too at this point as I'm sure it will be available in the not to distant future, if it isn't already...