"Plus 2 heavies" - Pepper slinging salt.

My guess is Ineos is not providing payload weights for the Trialmaster and Fieldmaster variants because they are (hopefully!) in the process of making changes based upon all the excellent feedback on the initial releases courtesy of this forum and other owners for model year 2024 and beyond. In other words, the payload for those trims (and perhaps even the base Station Wagon) is a moving target right now.
After thinking about this further - I could be dreaming, but for some reason I remember an early Grenadier brochure (not sure which country) that had an asterisk or sword icon or some other footnote at the payload figure that gave adjusted payloads for the TM and FM editions. Does anyone else remember that?