Unfortunately, the information provided in this prompt is inaccurate.

Firstly, the coordinates given (latitude: 35.3681488, longitude: -90.07672882) point to a location in Tennessee, not Illinois.

Additionally, without a specific town or county name, it is impossible to verify if a boat ramp named "River Road" exists in Shelby County, Illinois.

Therefore, no accurate information can be provided on the type of boat ramp, width, body of water, or permitted watercraft.