The guidelines you choose to follow, for any GxP purpose, should be selected based on the regulatory agencies to which you report. This in turn, should be more or less dictated by the location of your facilities, and the countries into which you wish to import your products.

The FDA is widely accepted as a reliable source and the FDA relies on the USP for specifics of MKT. As a start, you could look at USP chapter <1079.2> “Mean Kinetic Temperature In The Evaluation Of Temperature Excursions During Storage And Transportation Of Drug Products”. This has a nice explanation of the application of MKT. If you want something more general, you can always refer to our Vaisala whitepaper on the topic:
https://www.vaisala.com/sites/default/files/documents/CEN-G-Mean-Kinetic-Temperature-Application-Note-B211534EN-A-FINAL.pdf

Before you begin using MKT for GMP decision, please verify that the relevant regulatory authorities support the use of MKT for your application. For instance, it is not universally accepted to use MKT to resolve deviation encountered during shipping.