You will see it for yourself if you pass through Badaling: it's difficult to be alone on the Wall... Even in periods where there are few tourist (the winter), the site is under siege by tourists (both Chinese and foreigners) who visit for the day. The closer a site is to Beijing, and the more accessible it is, the more visitors there are! That means that, even if the Great Wall retains its impressive majesty, it loses some of its charm.
My advice if you want to get off the beaten track : spend the night and walk from Simatai to Jinshanling.
From Beijing, you need to travel by car or by bus and head 140 kilometers out of the city to the north-east. It takes around two to three hours by road until you arrive at the Simatai site. Try to arrive during the middle of the afternoon, when the visitors are heading back to Beijing and only those who intend to spend the night there will remain (i.e., very few indeed!)
Here, near the village of Dong Po, an inn that is very close to the wall welcomes travellers who are seeking a unique experience. You can spend the night and thus have the wall all to yourself at sunset and at sunrise.
Use the evening to explore Simatai. This portion has not been restored, unlike the more tourist-oriented sites, which is also what gives it its charm. With just a few minutes' walk, you reach the peak, which gives a spectacular view of the wall, the mountains and the forest, bathed in the warm glow of the setting sun.
Early morning call! Above all, don't miss out on seeing the sun rise above the Great Wall. Also allow for a good breakfast, because you've got a lot of walking ahead, from Simatai to Jianshanling, which is not (if you'll pardon the expression) a walk in the park. A friendly tip: it's better if you're in shape. But having the Wall to yourself is priceless. Ramparts, sharp peaks and honeyed horizons await your attention.
A walk along the Great Wall is a feast for the eyes. As you move forward, you pass watchtowers and observe the landscape as the guards once would. The greenery captures your glance everywhere you look. Forests, groves, and streams perpetuate as far as the eye can see. Covered entirely in granite and seven meters high, the wall is nothing if not impressive. I'll leave it to you to imagine the scenes of the past and the fortitude that these past soldiers must have shown. The guards had to spot strangers as they arrived, even though the forest covers 90% of the surrounding area.
Even though the hike is only ten kilometers long, allow between three and five hours. Between climbing the steps and guard towers, admire nature all around you as well as the stones that allowed this impressive structure to be built at all.
When you arrive at Jingshang, you'll notice that it has been restored and remains a nice place to be as well as a good opportunity to view the Wall without too many tourists around you. From here, you'll easily find transportation to take you back to Beijing.