the only thing I can suggest is figure out what axels it has and the ratings, that plus 10% will give you the approximate gvrw. you can go across a cat scale to get the weight, do your truck with you and a full tank of gas first, front and rear axels. then hook up and pull on so just your rear axels will be measured, get that, then pull the trailer on so just the trailer axels are on it and get that weight. the difference of your empty rear axel and loaded is your hitch weight, then add that to your trailer axel weights to get the current weight of your rv.