How to create an Editor for Imported Objects imported from a ScriptedImporter?

I have created a ScriptedImporter, that imports some json to a ScriptableObject i call JsonAsset. That works fine, i can manually edit the json and see the changes to the fields in the inspector. Now i want to create an editor so i don't have to edit that json manually. I have tried to do that with an Editor and a ScriptedImporterEditor, but every EditorGUILayout field i create is read only. I want to do this:

Load json from file via my ScriptedImporter. Deserialize the json to a JsonAsset. Select this JsonAsset in unity.

(Make some changes in the editor/inspector)

Serialize that JsonAsset to json into the json file. So that the JsonAsset and json match.

It wouldn't be a problem for me if there is a way to bypass the read onlyness of the JsonAsset as i wouldn't edit the unity object representation directly, but the underlying file.