Creating a turn around area for truck deliveries

Hello! I own a small ranch that currently can not get semi loads of hay, which is costing us about double the price. We have the place to create an area where a semi could back into, be unloaded and then pull out (perpendicular to the road). My question is, what size does this need to be for a driver to be able to do this? I can make the front of it pretty wide.

 

Hopefully the picture comes through. To give some perspective, the barn is 30 x 50 and the other smaller building is 20 x 20. The trees down the middle is a stream. The road is dirt. I marked where we were thinking of creating a pad (gravel). Its pretty level already, would obviously have it graded. Do you think this is possible?

 

I wish we could do that! There is a slope right off the main road.

 

Right, I don't want to cause issues for the drivers, which is why I'm asking what is possible and what is ideal (although I know I can't get to ideal, I'd like to get as close I can). I just don't know what size that pad would need to be, which is why I'm asking.