diff --git a/wagtail/api/v2/endpoints.py b/wagtail/api/v2/endpoints.py
index 73057e1f1..ba81ba2f8 100644
--- a/wagtail/api/v2/endpoints.py
+++ b/wagtail/api/v2/endpoints.py
@@ -94,57 +94,32 @@ class BaseAPIEndpoint(GenericViewSet):
             return Response(data, status=status.HTTP_400_BAD_REQUEST)
         return super(BaseAPIEndpoint, self).handle_exception(exc)
 
+    @classmethod
+    def _convert_api_fields(cls, fields):
+        return [field if isinstance(field, APIField) else APIField(field)
+                for field in fields]
+
     @classmethod
     def get_body_fields(cls, model):
-        """
-        This returns a list of field names that are allowed to
-        be used in the API (excluding the id field)
-        """
-        fields = cls.body_fields[:]
+        return cls._convert_api_fields(cls.body_fields + list(getattr(model, 'api_fields', ())))
 
-        if hasattr(model, 'api_fields'):
-            fields.extend([
-                field.name if isinstance(field, APIField) else field
-                for field in model.api_fields
-            ])
-
-        return fields
+    @classmethod
+    def get_body_fields_names(cls, model):
+        return [field.name for field in cls.get_body_fields(model)]
 
     @classmethod
     def get_meta_fields(cls, model):
-        """
-        This returns a list of field names that are allowed to
-        be used in the meta section in the API (excluding type and detail_url).
-        """
-        meta_fields = cls.meta_fields[:]
+        return cls._convert_api_fields(cls.meta_fields + list(getattr(model, 'api_meta_fields', ())))
 
-        if hasattr(model, 'api_meta_fields'):
-            meta_fields.extend([
-                field.name if isinstance(field, APIField) else field
-                for field in model.api_meta_fields
-            ])
-
-        return meta_fields
+    @classmethod
+    def get_meta_fields_names(cls, model):
+        return [field.name for field in cls.get_meta_fields(model)]
 
     @classmethod
     def get_field_serializer_overrides(cls, model):
-        serializers = {}
-
-        if hasattr(model, 'api_fields'):
-            serializers.update({
-                field.name: field.serializer
-                for field in model.api_fields
-                if isinstance(field, APIField) and field.serializer is not None
-            })
-
-        if hasattr(model, 'api_meta_fields'):
-            serializers.update({
-                field.name: field.serializer
-                for field in model.api_meta_fields
-                if isinstance(field, APIField) and field.serializer is not None
-            })
-
-        return serializers
+        return {field.name: field.serializer
+                for field in cls.get_body_fields(model) + cls.get_meta_fields(model)
+                if field.serializer is not None}
 
     @classmethod
     def get_available_fields(cls, model, db_fields_only=False):
@@ -156,7 +131,7 @@ class BaseAPIEndpoint(GenericViewSet):
         an underlying column in the database (eg, type/detail_url and any custom
         fields that are callables)
         """
-        fields = cls.get_body_fields(model) + cls.get_meta_fields(model)
+        fields = cls.get_body_fields_names(model) + cls.get_meta_fields_names(model)
 
         if db_fields_only:
             # Get list of available database fields then remove any fields in our
@@ -199,8 +174,8 @@ class BaseAPIEndpoint(GenericViewSet):
     @classmethod
     def _get_serializer_class(cls, router, model, fields_config, show_details=False, nested=False):
         # Get all available fields
-        body_fields = cls.get_body_fields(model)
-        meta_fields = cls.get_meta_fields(model)
+        body_fields = cls.get_body_fields_names(model)
+        meta_fields = cls.get_meta_fields_names(model)
         all_fields = body_fields + meta_fields
 
         # Remove any duplicates