Even the NMC ones need charging to 100% and leaving connected for a while to balance every now and again afaik
Li-ion batteries don't like being held at 100% too long or over discharged but an intelligent charger should manage that including balancing and avoiding problematic float charging but I don't know the ins and outs as to how well that is implemented on different cars and chargers.
Looks like back to the drawing board then as i bet not many were spec'd with a factory tow bar, that is super annoying that they go to the trouble of having different V5 details and different VIN plates on the ones that they fit a bar in the factory then