An RGG though, always has a "boss" ship that all others follow, so it will always spawn at 100%. In the RGG though, you can have it listed as GENERIC Merchant, or GENERIC Tanker or whatever class. As for where it spawns, where you place the RGG is the "center" point, but you can use the "RandStartRadius=" line (which defaults to "0.000000") to have it spawn anywhere inside of the radius of that figure. However, the group will always head toward waypoint 1. You can set "loop" points though, for the ship to choose a variety of different possible routes after Waypoint 1 is reached, which might be a bit easier to have variety. The player always starts in one single defined spot inside a Single Mission, and the RGG always spawns with a given radius of a defined location, but after that, with the use of "Loop" at the different waypoints, you can have all kinds of "chance" fun. The player's boat has to be at least 30+km away from where the group spawns, so that should give you plenty of chance encounter to deal with...