As far as what I think, if riding rando distances is going to reduce your quality of life because you'll be worrying about oxidative stress, then don't ride rando distances. I'm serious. Life's too short to spend it worrying.
I think there are about 1000 other things that should be bigger worries, if you'd analyze relative risks. Genital numbness comes to mind (don't know why lol). Hand numbness. Frostbite. Heatstroke. Hypothermia. A broken neck (don't know why lol). Food poisoning from convenience store food. Automobile accident on the way to/from the ride. Losing your spouse due to time apart. Skin cancer. Wild animal encounter. Feral animal encounter. That $h1# is all real. Oxidative stress from ultra events causing cancer is very speculative.
I think 3-5x per week at 20-40 miles with varying levels of intensity is a physically healthier life than is riding rando distances. We don't do this for our physical health.