best way to load 43,900#, 20 pallets, in a 53'

Single in nose, then double, double til 2/3 loaded, then another single and rest double. That will take space of 22 pallets with 1000 lbs light in nose. You may want to turn the single pallets to make them more stable. I'm you will get more saying I am wrong, but it would also depend if you have a heavy tractor or a lighter one.

 

All straight in
Single double single double to end
I actually prefer single single in the nose... and the doubles together and straight down the middle so about 4" of air space between pallets and the walls... save the trailer walls DRIVE CAREFUL...
Show up with half tank or less of fuel

Edit.
I'd do 2 singles in the nose then the rest doubled all the way back. You don't want the trailer axles all the way forward and be too much under 34000. You will be fine for 2 or 3 holes back from the front to achieve 34000 on trailer axles without going past usually hole 5 for 40' ca kpra rule. All straight in again.

 

This. Single, single, double the rest, but I prefer chimney block. First two against driver wall, second two passenger.

But I'd go single, single what ever you do.

 

Why chimney block? I hate doing that with regular pallets, with chep it isn't too bad. In the produce world sideways pallets are a pita at places that only have those smaller electric pallet jacks - the forks don't really fit in sideways pallets

 

Not necessarily turn the pallets sideways, just keep them up against the side bulkheads, just touching, opposite side, every other layer. I think it secures the load better.