Custom level editor project

We’re in the process of creating an RTS map editor with a strong emphasis on creating custom multiplayer maps.
However, we don’t want the full-blown feature packed UE4 Editor, but intend to create a custom version of it specifically for our game framework.
That is so our users can create maps with relative ease, with our specific gameplay oriented features.

The best approach we’ve found is that we need to walk through the editor code, learning how the Slate UI framework actually works, how it utilizes engine features, and then start removing the default widgets across the editor and start writing our own either from scratch or based on built-in ones, around our game framework. Unfortunately, the huge codebase and lack of (public?) documentation around actually modifying the editor make it very hard to jump start the process.

We’re looking for insights from the community and staff:
Are there any guidelines, documentation or other resources that can help us?
Are there any examples of this sort of modification being done?
Does our approach seem reasonable? are there any other approaches to go about it?
Anything that comes to mind - thoughts, ideas, regressions - throw it at us.

Thoughts for UE4 Staff/Devs:
How do you train new recruits regarding the engine and editor code? Since the source code is public, we believe sharing training methods is something that could really help the community

We are really excited to hear your thoughts on the matter and looking forward to see our project come to life. :>

This is not a matter of licensing. We already know about licensing issues around custom maps and modding.

Why not an In-game editor?

There was a twitch stream a few months back about extending/altering the editor. Maybe look for that?

We considered the option but we feel it would limit us in terms of the editors usability. we want a robust solution for our specific game framework.

Yeah I’ve watched it already but it’s more like a simple introduction and they didn’t even release the source code of it yet.

I not sure at 100% because the license have changed, but i think you cannot use the Engine Tools to make other tools or launchers or other things and put that public.
Source: [Question] Custom editor with game using some UE4 core tools - UE4 AnswerHub

Old License:

New License:

Anyway, you can make the editor in the game.

About this:

Unreal Engine 4 and the code don’t is “public”, you accept a license and is created by Epic Games, you can make, share, etc with the Unreal Engine community and members who have accepted the license.

*Correct me if i’m wrong.