I have made a video tutorial series on creating a minimap using a texture instead of a camera render. In the video I show how to achieve this and explain how it works.
Part 1: Unreal Engine 4 Tutorial - Minimap (Advanced) - Part 1 - YouTube
I go through getting a texture made for the level and then creating the material and widget so that it scrolls based on player location.
Part 2: Unreal Engine 4 Tutorial - Minimap (Advanced) - Part 2 - Player Icon - YouTube
I show how to add a player icon to the map and read the direction the player is facing.
Part 3: Unreal Engine 4 Tutorial - Minimap (Advanced) - Part 3 - NPC/Object Icons - YouTube
I go through the process to get points of interest to show on the map and move correctly based on their owners. This includes static and dynamic points of interests. This method is designed to be as easy for the developer to add as many points of interests that they want with little extra effort.
Check it out, hopefully you find it useful.
Any questions or if you get stuck, please just leave a comment somewhere (here/youtube) and I will help as best I can.