Had more time so I mounted the first fuselage doubler.
This lighter balsa doesn't require much pressure to lay flat so I just used 65 lbs of weight over pieces of MDF to press the two glued pieces together on top of some wax paper. Will let set overnight.
The glue actually started to cause the doubler piece to warp a little as I was spreading the glue due to the moisture it was absorbing but I'm sure it will dry flat now. :P