Don't forget the river rocks in your Teeyota.I ran 120 psi in my 82 mustang rear air shocks when i went to load hauling.
Hauled 45 Car batteries in the hatchback trunk once.
That was a tick over your 1400 lbs.
But I only had city roads to travel and less than 40 miles.
My 1947 Dodge truck of all things is sprung light and is on the snubbers at 1200 lbs.
Ford truck springs.