well generally it's a good idea, but should be developed some more.
but in fact, item multiplication is a bad idea, cos it'll affect world's economics too much making items like minigun n battle armor absolutely on everyone.
but multiplying some limited amount of caps would sound better immo.
for example there can be three types of caravan :
small one witch cost 5000caps and some waterbags. It's unnoticable on wordmap, but can be detected by anyone with 220+ outdoorsman, has short route (for example from NR to BH or from SF to NR).
medium one costs 20000caps n many waterbags. can be detected by anyone with 160+ outdorsman n have medium routes (from gecko to ncr or something)
big one cost 50k n loots of waterbags, can be detected by 100+ outdorsman chars n have long range routes (sf to vc or gecko)
after moving caravan to destination point your caps get multiplied depending on ur barter skill. for more roleplaying purposes caps in chart can be converted into some sort of goods, depending on the city u start caravan from, wich some sort of npcs can turn back into caps after u get to the destination point.
Or even deeper, each town get some goods, n trade between other towns n players are involved in these process. If u bring the needed goods from needed city u'll get more reward.
n ofcourse such trips should have kinda big cooldown, n requirements.