Allowing modders to access parts of a packaged game in the editor

So I’m working on a game, and I’d like to make modding support very accessible to the players. This game uses a heavily modified version of the basic shooter movement system. The game is mostly based around the movement physics of the player, so naturally, players looking to make custom maps or mods for the game would like to be able to have access to those same movement physics when developing their map or mod.

We would like to allow players to have access to this part of the game code while they are in the editor, but we do not want to provide the source code or blueprints associated with this part of the game.

Is there a way to package our character controller in a way that would allow modders to use it in the editor but not have access to the underlying code?

Currently the only way a modder can test their mod or map is to package it and drop the package into a mods folder and run the game, which still works, but it would be so much nicer if there was a way to allow testing against the player controller system directly within the editor.