I don't mean to sound flippant, but just fill 'em to 40-45 psi and call 'er done.
I'm running LT285/75R17 BFG KM2 M/T's at 45 psi and I am very FULLY armored with a roof top tent and all my recovery gear. I'm running at least as much if not more weight than you and my tires have been holding our fine! I have over 40,000 miles on them. But it is getting about time to swap them out.
I love the BFG M/T's but after about half lift, they start to get a little noisy. I'm thinking of going with the same size but with the BFG A/T's instead.