Noisy generator?
This is from the national park service website - pertains not only to trailer length but also the noise issue.
Maximum Trailer Lengths
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Maximum lengths for trailers, campers and motorhomes vary from park to park. The average maximum length permitted is 27 ft, but some parks can accommodate up to 40 feet in length. Some parks may have electrical hookups and dump stations. You should check with your favorite parks for their specific maximum lengths and available facilities so you won't be disappointed when you arrive.
Please note the following is prohibited: Operating motorized equipment or machinery such as a electric generating plant, motor vehicle, audio device in a manner that exceeds a noise level of 60 decibels at 50 feet; or if below that level nevertheless; makes noise which is unreasonable considering the nature and purpose of the actor's conduct, location, time of day or night, purpose for which the area was established, impact on park users, and other factors that would govern the conduct of a reasonably prudent person under the circumstances