hauling things does take some time refreshing and is huge creditdump if you push it.
if you want to profit from bonuses after cycle, go undermining with combat.
viper would be good for this. cheap and effective. choose a system close to your factions sector for your base, so you dont have too big of distance. at best take an anarchy system so you dont accumulate a big bounty on your head^^
did that with my vulture and made it to 10000 merits a few times^^