I too ride 90% solo.
Some of the riding is fairly desolate areas.
Two years ago I wrecked, and gashed my knee. With no first aid kit, I bled until I got to a bathroom, approx 5 miles away.
Then I started carrying a very small first aid kit. I always carry basic bike tools, a spare tube, lights, emergency food, and early and late seasons when the rest stops are not open, extra water. For the true emergencies, I carry my cell phone, credit card, health insurance card, and a little cash.
There are stretches on the MUP's where there is no one for miles. Some paths are heavily wooded. I have often wondered if I should carry a small pepper spray for wild dogs, etc. Have not done that yet.