SNX ModLoader
SNX ModLoader works based off the Load Level Instance by Name node since it can be used to load files purely based off a string and not an actual reference to a file.
First start with making a new level in the /Content/CustomContent folder, if CustomContent does not exist then just make it yorself.
The name of the level will be used for mod loader, so if you name your level TestMod you'll need to type TestMod in the mod loader menu.
Once the level is made open it up and click on Blueprints > Open Level Blueprint at the top of the level view port.
With the level blueprint graph open add a SpawnActor from Class node from the Begin Play event to spawn in your new blueprint which holds all your new code. Then drag off the Spawn Transform from the Spawn Actor node and choose Make Transform this node doesn't need it's numbers adjusted spawn actor just needs a valid transform input to spawn.
Credit to YuriLewd for the original process