The type of caravan doesn’t affect the tyre pressures. It’s car loading which includes the caravan noseweight applied to the towball. But aren't your tyre pressures detailed on a makers label generally on the B pillar. It’s normal to show light load, full load and a towing load. If towing load isn’t shown you would go with the full load figure. The only difference towing makes is that the load imposed on the towball ( noseweight) is considered to be a part of the cars total load. Do you have an Owners Manual for your car?
Whilst going up 4 psi from normal cold pressures will help, it’s quite an old rule of thumb. My car is 7 psi extra on the rears and 4 psi on the fronts for fully laden/towing. With the various types of tyres and aspect ratios the OP really needs to get the correct tyre pressures for fully laden and or towing. Otherwise he could be in for a big bill if uneven tyre wear should result from incorrect pressures.