Spare tubes,tire wrench kit , extra headlamp and batteries,extra coat and socks and food and waterI wouldn't put a rifle or bow rack on the bars just in case I eat crap and crash I would rather have my rifle on my back

This. Took a few spills when I really wished the weapon was not on the handle bars. Besides spills, that also subjects your weapon to severe vibration and rattling. Not good imo. I like my gun or bow strapped securely on my back. Your body is a great shock absorber.
Need something for flats. Something to tighten anything that comes loose. Chain breaker came in handy 1 time I broke a deraileur and rode in with a 21 speed and rode out with a 1 speed.
Can't see dragging a trailer. I like to stash it in a convenient spot, even if I have to go back aways. Makes 1 trip out with an elk possible.