I'm expecting tons of wood chips to be dropped off in part of my yard every day this year, and am wondering what I need to do so the arborist can easily drop them off as close to where I want them as possible while staying happy (not sinking into swampy soil, or tractor eating ground)?
The usual solution to avoid sinking into soft ground is to release some air from your tyres so that they bulge more. That increases the contact area with the earth, distributes the weight of the vehicle over a larger area, and reduces the likelihood and depth of sinking.
It is highly unlikely, however, that a commercial service will do this for you. They want a place where they can quickly pop in, drop off, and leave. Ideally, the driver wouldn't even have to exit the cab of the vehicle.
If that's the case then you have no option but to control/modify the route that the trucks will take once they come through your gate.
If you have an existing, all-weather driveway, then use that. If you don't have an all-weather driveway, or the condition of your driveway is 'marginal', then you want to divert the trucks off it as quickly as possible.
Dad was a logger. Brush piles, and huge volumes of sawdust and wood chips were a by-product of the logging/milling operations he was involved in. The local soil is sandy, but low spots exist that turn swampy/boggy in the wet season. Their solution for temporary roads through boggy areas was a 50cm deep elevated roadway made of woody debris.
Paths turn to muddy bogs due to the hydraulic pumping action that occurs as tyres drive over a particular spot. If you create a deep enough pile of chips, it will be free-draining, and hydraulic pumping won't occur at soil level.
So, my suggestion would be for you to divert incoming trucks from your driveway as quickly as possible and get them to dump their first load straight away. You should sculpt the pile into a type of gentle off-ramp. Subsequent loads should extend the ramp and increase its height. Repeat until the height of the ramp is "decent" (around here ~50cm supports logging trucks). From that point on just extend the length of the elevated woodchip road as needed and route it wherever you want.
About the only maintenance required is to occasionally rake-in the chips from the sides to the compacted ('rut') areas, and to occasionally top up (level) sections that compact more than others.
I've only just noticed your previous question about pigs and woodchips. Assuming that this is related to that, if/when the woodchip road is no longer required you can fence it off with an electric fence and let the pigs in to eat/dismantle the road. What little the pigs miss will quickly break down and the grass will return.