I would go with something back portable incase you need to leave the comfort of your vehicle during a bug out.
My BOB consists of a frame mounted ALICE pack and a LBV. With this setup I can get 3 days to a week depending on how far I stretch my supplies. My bug out firearms are either my daily carry XD9 or G17 and my AR. I plan to bug out by vehicle which would allow me to carry more food,water, and ammo but the BOB is setup for not having any kind of support at all. Never know when driving a vehicle might not be the best option or if/when you will break down.
I personally go though my BOB on the 1st week of every month to inspect everything to make sure it's still good to go and nothing in the medical or food front is expired or ripped open or anything like that. I also take that opportunity to rotate the water that I have in the canteens for fresh water.
This is an old picture here. Some things have been removed and some things have been added since then.
Here is what I carry everyday. Not necessarily on me into stores and stuff but if I leave the house it rides in my car
The kit above will get me home if I'm out and about. Enough food for a day, spare ammo, ect. Never know when civilization will end while your shopping at your local wally mart LOL.
Some guys have even built I.N.C.H. kits for long term bug out survival. I forgot what INCH means right off the top of my head but these are some VERY well thought out kits that could keep you alive and mostly comfortable for a long period of time.
Even having a 3 day BOB will put you well ahead of a large majority of the population out there.
ETA-if you are interested in prepardness before, during, after a large natural disaster or local disaster or what not, check out Zombie Squad
We use zombies as a metaphor for disaster. Since if you are prepared for zombies you are prepared for anything short of being at ground zero of a nuclear blast or asteroid strike.