Molly Bolts are a good choice among others. If you choose to use Molly Bolts, the ones you most likely want are "1/8" XS". The XS meaning extra short...needed due to the very thin luan walls.
I like the Molly's, as I feel they get a bigger/better bite on the backside of the wall than rivets do.
'04 GMC Sierra 2500HD, CCSB, D/A, MaxBrake, B&W Companion, Retrax Pro, AR Power Steps
2013 Rockwood 8289WS w/Diamond pkg
1969 Camaro RS/SS Convertible
Dad's old 1968 Empi Imp (recently recovered from under 21 years worth of boxes/dust)