I`m sure its a wood frame , you've got all you need in the diagram from Lance .
Look inside the camper at the ceiling , the trim that runs side to side every 4 foot will give you a starting place to use the Lance layout ,open the vent over the bed and transfer from ceiling to roof , the trim is centered on a framing member , they are 3/4 " wide . The roof is foam core between 3/4" wide x 1 1/2 " framing W/ luon under the sheet aluminum roofing
I would defiantly not just attach to the aluminum and luon . I would defiantly look for framing to screw to .
I just put 4 more 100 watt panels on my Lance Legend 500 added to the 140 watt that I installed years ago .
Use this
dicor tape under the panel mts and seal over the screws and around the mts with dicor self leveling caulk
