Ok, it looks like you can do FsmBool[] and FsmInt[], but it throws the below to the console. Any ideas how to clear the error?
ArgumentException: GUILayout: Mismatched LayoutGroup.Ignore
UnityEngine.GUILayoutUtility.BeginLayoutGroup (UnityEngine.GUIStyle style, UnityEngine.GUILayoutOption[] options, System.Type LayoutType) (at C:/BuildAgent/work/7535de4ca26c26ac/Runtime/ExportGenerated/Editor/GUILayoutUtility.cs:208)
UnityEditor.EditorGUILayout.BeginHorizontal (UnityEngine.GUIContent content, UnityEngine.GUIStyle style, UnityEngine.GUILayoutOption[] options) (at C:/BuildAgent/work/7535de4ca26c26ac/Editor/MonoGenerated/Editor/EditorGUI.cs:4682)
UnityEditor.EditorGUILayout.BeginHorizontal (UnityEngine.GUILayoutOption[] options) (at C:/BuildAgent/work/7535de4ca26c26ac/Editor/MonoGenerated/Editor/EditorGUI.cs:4678)
HutongGames.PlayMakerEditor.VariableEditor.FsmBoolField (UnityEngine.GUIContent label, HutongGames.PlayMaker.Fsm fsm, HutongGames.PlayMaker.FsmBool fsmBool)
HutongGames.PlayMakerEditor.ActionEditor.EditFsmBool (UnityEngine.GUIContent label, System.Object fieldValue, System.Object[] attributes)
HutongGames.PlayMakerEditor.ActionEditor.GUIForFieldTypes (System.String labelText, System.Type type, System.Object fieldValue, System.Object[] attributes)
HutongGames.PlayMakerEditor.ActionEditor.EditArray (UnityEngine.GUIContent label, System.Type elementType, System.Object fieldValue, System.Object[] attributes)
HutongGames.PlayMakerEditor.ActionEditor.GUIForFieldTypes (System.String labelText, System.Type type, System.Object fieldValue, System.Object[] attributes)
HutongGames.PlayMakerEditor.ActionEditor.EditField (System.Object obj, System.Reflection.FieldInfo field, System.String labelText, System.Type fieldType, System.Object fieldValue, System.Object[] attributes)
HutongGames.PlayMakerEditor.ActionEditor.OnGUI (HutongGames.PlayMaker.FsmStateAction action, Boolean debugVariables, Boolean isPreview)
HutongGames.PlayMakerEditor.StateInspector.DoActionGUI (HutongGames.PlayMaker.FsmStateAction action)
HutongGames.PlayMakerEditor.StateInspector.DoActionsListGUI (HutongGames.PlayMaker.FsmState state)
HutongGames.PlayMakerEditor.StateInspector.DoActionsPanel ()
HutongGames.PlayMakerEditor.StateInspector.OnGUI ()
HutongGames.PlayMakerEditor.InspectorPanel.OnGUI (Rect area)
HutongGames.PlayMakerEditor.FsmEditor.OnGUI ()
FsmEditorWindow.OnGUI () (at Assets/PlayMaker/Editor/FsmEditorWindow.cs:93)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Applications/buildAgent/work/b59ae78cff80e584/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)
Note this only happens when changing the number of variables from 0 to 1 or something of the sort. Still testing to see if this actually works in my custom action.. if it does then this is perfect for what I need.