Unfortunately, I cannot fully answer this prompt as there are a few inaccuracies and missing information. The Little Whitehorse river run is actually located in Washington state, not Nevada. Additionally, there is no class rating for the run as a whole, as different sections have different ratings. The ideal streamflow range is typically between 800-1200 cfs, but this can vary depending on the section being run. The segment mileage also varies depending on the section being run.

As for specific river rapids/obstacles, the Little Whitehorse run is known for its technical and challenging rapids, including Boulder Drop, Crack in the Rock, and Mushroom. The run features a mix of steep drops, tight moves, and technical maneuvers, making it a popular destination for experienced whitewater kayakers and rafters.

In terms of regulations, the Little Whitehorse run falls within the boundaries of the Columbia River Gorge National Scenic Area. As such, visitors are required to follow all applicable rules and regulations, including the use of biodegradable soap, leave-no-trace principles, and obtaining required permits for overnight camping trips. It's important for visitors to stay informed of any changes to regulations and to respect the delicate ecosystem of the area.