Hey you loggers, I've got a question for you.

Self loading trucks generally have 30-35' reach to the side.
The further out the boom has to go, the less it can handle.
The closer you can get the truck to the deck, the better for everyone.
The lift capacity at 6' vs 30' reach is a factor of 4...
My forwarder grapple would pick up 6500# at 6 feet, 750 at 36 feet.
Setting logs over a fence is not difficult, but asking for trouble.
Kinda depends on the talent of the operator.
If possible, remove the fence while the truck unloads, put it back afterward.
The driver that will be delivering should get eyes on the location, and they'll be able to tell you precisely what they can and cannot do.
Anything else is speculation based on theory.
Loggers never believe anything until they've seen it first hand.
I know I don't.
Get the driver out, discuss your concept with them, and work out something mutually beneficial.

 

Most of the self loaders use what is called a "heel boom" which means they pick the log or pole about 1/3 from the end and "heel" it then swing it over and set the far end down and swing the grappled end where they want it.

Other machines are pretty massive and can grab multilple poles/logs close to the middle and swing them out pretty far, but I'm guessing you need the self loading truck type.

I haul treated poles and have a few videos on the subject.

 

First 3 pix are the heel boom variety using an Olympic crane and the final 2 pix are with a Lemco crane which has more aas.

 

We used to get a tri axle load delivered that would last about a year and half for 1200 if i remember right. But the last few years we've been buying by the cord for 150. Mixed hard wood. A ton of ash because of the blight