I echo the above comments,she is looking good Zolly.If I may make a suggestion.I would be tempted to shape a couple to pieces of plywood that temporarily bond between the bulkhead ears,one fore and one aft.You could then plank the underside without fear of damage and if you secure the plywood pieces to a board,extremely stable.I have found that having the model solidly fixed upside down makes the planking infinitely easier than trying to plank this area with the model on it's side.
Kind Regards
Nigel