A bit undecided on what pressure to have the tyres when towing a Caravan. Nose weight of van around 80-90Kg and weight around 1650Kg. Car will have two adults in the front and lightly loaded in the load area with probably around 50kg of items. Car is an L405 2020 running on 21" tyres, current pressures are the indicated 35/38psi which shows 4 people in the car on the label.

Would it be necessary to increase the pressures right up to the heavy load levels or somewhere between the two levels?

Try in between and then full load. I didn't change pressures when towing with my D3, it was fine. My audi though..had to whack all 4 up to max load pressures to get it feeling OK. Yet to try the l322 but I'll be trying mid point then full load

We're 2 adults, 2 kids 9 and 12, 2 staffys and normally decent load in the boot, same nose weight as you

L322 not L405 but… Cabin loaded with car bits, fully fuelled. Trailer with small track car but also tools and spare wheels. PSI was set at mid point when cold. However when warm had increased to closer to full load values. Was perfect on 220-mile round trip. No wandering or “bouncing” at all.

No caravan experience, but with the trailer my rear tyres are inflated to 42psi, which I think is what LR recommend and has been fine. Fronts stay at normal 34psi. Only Range Rovers since 1988

^ Thats what I put in for our larger horse box (3.1 tonnes loaded, twin axle). I usually drop the rear back to 36 afterwards as it feels a bit firm.