I would suggest two bags.
Bag one is sling bag with a tape/disk, 9 volt or AA's what ever you take, multitool, warm cards XLR and a folding table mic stand, hard wire lav mic, polarizing filter, small reflector and a roll of tape.
Large run bag- Video cable, 2 long XLR's, bag of adapters for video and audio, small multimeter, paint brush, small tool kit. **** loads of batteries, lens cleaning stuff. Spare lav mic. Camera cover, large reflector, spare bulbs for sun gun, zip ties.
That's all I can think of off the top of my head. Keep in mind I've collected this stuff over 19 years of shooting. I still have the first bag I bought. I found it in my locker when I was moving to my new job. Think it was $24 or something and held 2 3/4 inch tapes a XLR cable and two NP batteries.
acton