That wall should ave bracing in that location for a TV mounted on the opposite side in the bedroom. You should be able to tap around to find it. I'm not sure how much weight a shelf there would hold, but I wouldn't put too much up there.
2013 Z-1 251BH | 2011 Nissan Armada | Curt WD hitch with no sway control 2014: 20 Nights & 1338 Miles 2013: 23 Nights & 1200 Miles 2012: 10 Nights & 254 Miles
Studs are aluminum and most stud finders will detect them. Also since the interior paneling is 4 ft wide, find a joint and from there, most studs will be on 16" centers. Use sheet metal screws. Drill a 1/8 inch pilot hole to verify you are on a stud and them drill the proper size for the screws, better to be undersized than too large. Weight capacity is more likely dependent on size and number of screws than wall strength.