After the Silver Shroud quest.. Where is the best place to meet the Manta Man (random encounter)?.

There is no best place, its entirely random, and just as likely to happen at any random encounter spot as anything else that could happen there.

Yeah, seems this game has the same random encounter system as Fallout 3 and Skyrim. There are places where they can happen, so try to find them and go between them until it happens.

That's what I'm asking for. Bezt two spots to alternate between.

There's also the problem with types of spawn points. (Skyrim had road, wild, and town specifics).