Caravan is not much efficent way to get caps.. one run is 2-10 mins + waiting till deport, you may die, not even 100% chance to finish, reward 800-2k caps
imo there are 2 major ways to get caps :
1. from npc traders - sell stuff for caps to npc
Im selling combat shotguns to same 10 traders with my alt while im playing with my main char (moving on wm or smthing), find few traders and craft/sell to them.. 200k+ caps from traders is no problem during one night if you got mats, It is little worse during day.
2. footlockers - alot caps from them + stuff (bps, rares) for sell to other players
or just be lucky and find vertibird