With no restrictions except that it were to be a firearm that could reasonably be added to a BOB (i.e. no AR-15's or AK's), I'd toss the AR-7 in the bag with a full size pistol in 9mm or .45 on top.
I have a newly acquired AR-7 in my BOB with a 1911 .45 on top. I wouldn't want to defend myself with a AR-7, or kill a barn swallow to eat with my .45