Whenever she eliminates, move her pile to where you want her to do it all the time. That works well.

I'd suggest for the first weeks you have the dog, to take her out for elimination on a leash and take her specifically to that area to do it. Reward her for success. Our dog prefers to use just one spot for defecation, and yeah......it can become a minefield as evidenced recently when the snow melted. LOL.

It may or may not work, depending on the dog's social history, but it's worth a try and beats moving piles of dog poop around.

I think it's all going to depend on the dog as to whether they'll use the area and if they can be trained to use it. Some dogs will refuse to go on the surfaces you mentioned whereas you may be able to train others to use it.
If I had to put in a dog run my choice of surfaces would be either a fine, splinter-free bark or the astroturf that many homeowners are using in their yards these days.

I think you should consider fencing off the dog run area and then installing a gate on the outside (for your access) and a dog door thru the house wall so the dog can use it whenever it wants. With that setup the dog won't have a choice to go elsewhere when you want it to use the area.

Your other option is to just pickup after the dog each day.

When you get the dog, find out while walking it if it has any preferred areas annz is absolutely 100 percent correct. Calliope also has a a good point. While it is best to try and leash walk a dog several times a day everyday, supervisiong a dog while eliminating for the first year or so will help out greatly. While out on walks give her the command to pee or do her business be sure and praise her do the same in the area in your yard where you want her to go, that way when you do let her out in the yard, she will know what to do and where to do it....