After conducting research, it appears that there is no official information available regarding a boat ramp named Sophie Lake Road in Lincoln County, Montana. Therefore, I cannot provide accurate information about the type of boat ramp, width, or permitted watercraft.

It is possible that this boat ramp may be an unofficial or local launch site that is not maintained by government agencies. In this case, it is important for boaters to exercise caution and use their discretion when launching from this location. It is recommended to contact local authorities or boating organizations for more information about this specific boat ramp.