Hello Kim,
I can't offer any advice regarding the mirrors, others with Galaxies will be best placed on that point, But it will also depend on how old the car is as we are now on the Mk3.
But when towing a substantial trailer liake a caravan tyres should be run at the recommended pressure for the fully loaded car. Details vary depending on the model of car and the size of tyres fitted, so check with you vehicle handbook, and most cars have a label somewhere that also details the recommended tyre pressures for different loads and speeds. Each manufacture can choose where to put this label, sometimes its in the glove box, door jam, under bonnet or in the boot.