Many trailers (such as RV campers) are constructed with 2x2 wood studs sandwiched between the aluminum skin and some interior wallboard (usually 1/4" paneling). I believe that these would hold your weight (perhaps with some flex), but you must use suitable anchors.
If you can reliably set 3/8" lag screw eyebolts to a depth of at least 1", properly piloted, they won't pull out at your weight. You'd want to pilot with a 3/16" bit marked for depth (1" plus the thickness of the wallboard).
Try to avoid hanging at the center of long walls where no intersecting walls lend support. Points near wall and ceiling corners will be most stable. Once the hammock is in place, load it slowly and observe any movement or sound that could indicate failure. Leave adequate sag in the hammock, as the straighter it is the more tension it places on the walls and hardware.