Some comments from someone that's hauled stuff for 10+ years (probably 50K miles with something on the trailer.)
Start with Grade 70 chains and binders properly sized for it. Don't know I'd go as far as one chain per corner of the tractor, but some like that. For sure you want chain going out from each corner, but for my money, it can be one chain on each end of the tractor.
When I load my tractor, I watch the rear of the truck and I can see the bumper lowering. Measuring would add to the accuracy. If you are really in doubt, you could hit a grain elevator or a moving company and probably get individual axle weights on your rig.
Adjust the chains tightly. When you start out, stop at 1, 5, 10, and 50 miles to tighten them. I always have it where I can see my chains in the mirrors, so I can watch for looseness from the cab. I've known guys that haul new tractors that let part of the air out of the tires, chain them down, then air up the tires. Instant tight!
Every time you stop, walk around the trailer, checking each chain, each hub for heat, and each tire for heat.
Check the air in the tires every morning. Were I doing it, I'd have two mounted spared for the trailer, along with lug wrench, jack, etc. When I towed with a 3 axle gooseneck, I traveled with THREE spares for it.
Going that far, I'd want good tires all around (trk and Tlr). With the trailer empty, I'd try stopping with only the tlr brakes to make sure they work. My experience (six wheels braking) one or more were NOT working at any time. If in doubt, might drop the tlr off at a good shop to have them check it out. Heading down a long hill is not a good time to find out the brakes are not working.....
For the truck, flush the radiator, new oil and filter, maybe a tune up to give it all the help it can get!
Loose stuff on the tractor or trailer will fall off. I noticed when my Bota was delivered, the driver had folded the seat forward and hooked the seatbelt over it. Told me they set there and bounce in the wind if you don't!
I'd try to hit the big cities at non peak times. Keep your speed reasonable. Stop to rest often. Enjoy the ride!