Update ..
Following a query on the "other" forum, I have been made aware of over-voltage protection units as per the following link.
https://www.aeroakku.com/CHARGER/-Re...a2390bcc34cf06
At first sight, this looks to be the sort of thing that I had in mind.
I still haven't got a good enough handle on the whole electrical situation to know whether I'm barking up a sensible tree here or not (as I've said before, electrics isn't my best subject) but I thought I'd post the link for reference and also in the hope that others with more knowledge of electrics than myself might comment.
Its probably worth repeating at this point that my concern was initially sparked (pun .. sorry) by a warning on the casing of my Magneti Morelli LiFePO4 batteries against charging them at over 15 volts.
As an electrical innocent myself, I have no idea whether the addition of one of these units would render the WHOLE charging system completely safe when used with an LiFePO4 battery .. I'm just trying to cover the aforementioned warning against over-voltage charging of the battery.
It seems logical to me that, if over-voltage charging should occur, merely isolating the battery would not be sufficient protection as the charge coming from the alternator needs to go somewhere (and I suspect the reg/rec wouldn't like it very much). Therefore I would be considering using a unit such as the one in the link to totally kill the electrics and stop the bike, in the event of such a problem.
It may be a daft idea .. I dunno .. that's why I'm putting it up for discussion.