Saris makes more than one rack that will work in a 2" receiver. We use it typically in our toad, but also have used it in the motorhome directly. It is very secure and will fold up out of the way when the bikes are off it. Here is a link to the model we have, but there are others as well. Good quality products. Prices will vary, shop around.
http://www.saris.com/bike-racks/vehicle-racks/hitch-racks.html?page=shop.product_details&flypage=flypage_images.tpl&product_id=72&category_id=8