Just put a limit to the number of vans that can be used a fed and it's a win-win for both sides
only allowed 2 vans out at the same time or something and not allowed to pull another until one despawns or is destroyed, profit
That's just down to your settings then, I hover around 90-140 in most places unless there's a lot of smokes (bank prison fed cartels etc), 7700k @ 5ghz & 1060