RNP falls under the Anderson Parks Dept. The Parks Dept has general hours of operation for all their parks which can be found here:
http://www.hmba.org/smf/index.php?topic=5437.0 However, they see the care we (mtbikers) take of the park. They realize we build and maintain all the mtbike trails and, as a result, we are very legite users of the park. Since they started gaining our trust years ago, they have quit shutting the gate at night. They know we are protective of the park and the trails in particular. They have not "pulled the reins" on night riding yet. Only the parks dept can grant permission to ride beyond specified park hours. However, they have not said "no" either. I will try to get a definate answer from them. But for now, I don't think anyone will be hassled for riding at night. Officers go in and out of the park and they are not loolking for mtbikers. To my knowledge, no mtbiker has ever been negatively confronted by the police, parks dept, or any other authority at anytime...day or night.
Currenty there is a lot of night riding going on at RNP. I think this has a huge impact on non-legit park users. Keep riding and I will try to get the proper authorities to make an offical statement on night ridiing.