Bet the Land Rover alternators were rated at huge currents.
You don't win anything by having an inverter. While it is true the transmission losses at 240v are less than at 12v or 24v, you have the loss caused by the inverter itself.
There are a good choice of 12v driven inverters these days, so anyone who needs one can stick to a reasonably standard alternator and stand a chance the man with a van can find one if you break down.
Plenty of recommendations on this site for heated clothes.
