They are not!
I have yet to see a mention of insurance co even mentioning LFP let alone imposing clauses.
This is probably because 99% of installs in caravans are in dedicated lockers sealed from the inside of the van and vented outside. It's a requirement from LA days.
The thing that I find worrying is that many just wire the LFP in parallel with the LA starter and rely on thin wiring and the BMS to control the charge**. Which may be fine in the case of some cars when the alternator only puts out 14.4v but not in the case of my latest that charges at 14.8v so I've had to fit a Renogy 20amp B2B charger and turn it right down so it doesn't draw too much over the cars wiring.
** I don't like only one layer of protection, it's why when younger I always wore
no I'd better not go there😱🫢😀