When flying FPV for an exact purpose, it allows you to prepare for special situations but I have learned all too well, Murphy's Law is rough... Drone Racing in general helped me out here I feel but let me show you the type of checklist I make before a gig.
This is where I start because above all else, I make sure that I can be mobile with what I need to fly if the situation arises. I have shown up to a gig, unloaded at HQ thinking we were going to have great comms the whole time but as we know, things happen. Making sure I can fly from wherever "on the fly" is a must.
I make sure to have my Radio / Goggles with their accessories and at least 6 batteries for my main craft and 2 for my goggles. In the pouch area besides that I make sure to have my handy prop tool, lens cleaner, extra pieces of Dual-Lock and prop nuts. Props are in a hidden compartment on the back of the backpack along with GoPro / Insta360 batteries and accessories. Of course we have a toolkit equipped with a soldering iron plus the basics.
Just that setup right there with my drone attached to the outside of the backpack will get me in the air and ready for most situations... baseline covered!
-HD Camera Bag-
If I need to stay mobile, the backpack will have batteries and the drone will carry the HD Camera but when I have the luxury of being set up at a HQ, I will use this HD Camera Bag.
It carries pretty much all the HD cameras and accessories I could want. Multi-Chargers, ND Filters, SD Cards, lens cleaners and more. I'll just take the needed stuff and put it in extra compartments on my backpack if I know I am going to be mobile.
I have been getting flak from my co-workers by not having a pelican case but when I do adapt to that, this will be the bag it takes place of.
This important case has all of my batteries, chargers, random tools and adapters that aren't 100% necessary but have proven useful many times. This includes xt30 to xt60 adapters (both Male and Female) heat gun, parallel charging boards, Laptop, different types of antennas and random props.
I try to fit my Director's set of goggles in here also but most of the time they live in a separate case so they can carry it with them if needed.
With all of that, we are pretty much ready for anything that the world can throw at us. Of course there are some factors that will just stop us from flying which we cant help like nearby police chases with helicopters overhead, insane wind gusts or just the director didn't get a chance to fit you in... besides these types of acts of God, we are ready!!