Even though I'm using the term BOV (bug out vehicle), I'm not going to be referencing a BOL (bug out location). This is more for mid-long term mobilization & deployment for a group.
Militia's are generally lacking after the 72 hour mark, & my input has been that the individual needs a 1 year supply of food/water & a way to move it. It may be up to the leaders to dictate how much to take & what items to bring in the initial phase of deployment (like helping out in a natural disaster 3+ hours away). This is just some concepts to look at and consider.
"Bug Out ___" has become a bit overused in the last decade, so when looking for ideas I tend to search niche markets. For vehicles & trailers "overland" seems to be the best options I've found. The jist is; going to a secluded place with friends & family, & staying there for days, weeks, & sometimes a month+.
There's many things one can do to their vehicles, a good place that I've recently found for input is; https://www.youtube.com/user/ExpeditionOverland/videos
If one has the means to tow, trailers are a great investment. One can just hook up & go! Some may op to build their own, like this; https://www.youtube.com/watch?v=QmR9BMtzMtk&t=109s Others may choose to buy a trailer already built, like this one; https://www.patriotcampers.com.au/camper-trailers/x1-h/
(look at USD & not AUD price)
Be sure to consider setup speed. Overlanders strive for setup/breakdown time to be under 30 minutes, most can do it in under 15, which is great for militia purposes when mobility is key.
Another concept to be looked at by leaders is specialty trailers, trailers that have a designated purpose like power, housing, waste, HQ, toy haulers (for scouting, medivac, & more), etc. here's an example of temporary shelter; https://www.youtube.com/watch?time_continue=6&v=6Wv2-fYmBvE&feature=emb_logo
When choosing a vehicle make sure to balance the cost, mpg, & towing capacity. Definitely look at reliability as well, this channel may be helpful to weed out the crap brands & individual model issues; https://www.youtube.com/user/scottykilmer
Hope this help in concepts for you and yours.