While most parts of the park remain off-limits, you can still take in some fabulous views of Cambodia below and you can also see some of Khao Phra Wihan in the distance. A few Khmer-era remnants, including the very evocative carving on Pha Mo E-Daeng cliff, are also accessible.
Khao Phra Wihan National Park has bungalows, but they're currently not available to the public. The campsite, however, is open.
There are a few restaurants (generally open 6am to 4pm) along the parking lot and snacks are sold at the visitor centre.