Real world Topography for UE4

[CUBS]

Hey guys, first post I'm working on new project after completing a big modding project for Day of Infamy a while back. Radu suggest I ask around here. So if this post is in the wrong spot blame him 1000%. 

Basically it's a rather large mod that's in the works for PUBG. And I'm trying to get a jump ahead of the mod tools whenever they get released basically to start the project I want to get the real world topography data and create. Kind of an open world level of a specific real world location I had in mind. Now I've used UE4 since launch and have used a few methods for generating and extracting topographic data based heightmaps. It seems there's some decent tutorials on the basics of it but anything further than that I can't seem to find. 

I really want to take a real world location that I've picked out which is about 27,000 km sqand scale it down to around 8-10 km sq in UE4 to meet the pubg standard map size. I was wondering if anyone here has any information or experience with this type of terrain creation. Generally I don't need it to be perfect as it's gonna be sort of a canvas to create different cities and towns on. I'm sure it will be heavily modified as it goes on. But I think using topography would be a great place to start for a general feel of this realworld location. It would be nice to beable to generate some rgb maps as well for material layers and blending. But I'm open to hearing all sort of ideas on the best way to recreate this into a manageable terrain. Not opposed to manually creating in either I've considered world machine but don't have much experience with it.