First, based on your posts and the objective stated, there is great risk of failure for this. The risk might also over-reach the benefits, i.e. when you and the swing fall, the physical damage may be more than the benefit of the swing.
If you use a stud finder you'll be able to locate the bottom chord of the roof trusses in your RV. They may be 2x2's of wood or they may be aluminum tube. A call to the mfg should straighten that out. What I'd suggest is to have two steel brackets that will accept a string of fasteners or a larger plate bracket that spans two or more ceiling rafters. You will need a hanging bracket that spreads the weight out along the length of the ceiling rafter or across multiple rafters.
One more warning: The roof framing of your RV is engineered to hold the weight of a thin panel, a few light fixtures, and support, in conjunction with the rest of the truss, the roof membrane. It is not designed to hold weight located in a small area.
If you do go forward with this, set up a video camera for the first use. The video record may be of some value.
