Seems like I was a bit too enthusiastic and didn't do my homework correctly. When looking at interior pictures of the Nieuport, it seems like the sides were definitely not made of wood, just the linen coverage of the airframe.

John, I’m pretty sure the side panels were wood from the back of the cockpit opening forward.

It’s modelling..no animals were injured in the making of this movie so to speak…have fun..that’s what it’s about

John vd Biggelaar (@johnb)
The plywood on the sides of the Nieuport 17 fuselage is exactly how John Healy described it.
@j-healy
It starts up front at the engine firewall, and ends right at the vertical post frame just behind the pilot's seat. This vertical post is located just behind the rearmost portion of the cockpit opening. It's purpose was to streamline the round engine cowling to make a smooth transition to the flat sides of the fuselage behind the engine. It might have also offered some strength and made the fuselage more rigid.

This I beleive is a Nieuport 11 drawing. The Nieuport 17 would have been similar, but you get the idea.

From there back you would see fabric covering on the inside. Some planes had a fabric covering behind the pilot's seat that would have been laced up. It would act as a wall divider, sealing up the rear fuselage section, and could be removed by unlacing it, (just as a person would tie or untie their shoes). This would allow access to the interior portion of the rear fuselage.

I think your plywood rendering looks good. If you are concerned about the grain being too prevalent, you may try using a piece of softer balsa wood, or even bass wood. I would try to keep it as thin as possible, because you might be able to see the upper top edge of the wood when looking down into the cockpit.

Personally I like the mahogany wood you chose. It's nice to get a different color stain on the plywood to liven it up a little. In some pictures I have located on the internet, they show the plywood was a series of thinner small strips that were glued in position at a 45 degree angle to the top fuselage longeron / stringer. If you really wanted to, you could remove the wood and cut it into thinner width sections. Glue it in place at the 45 degree angle, stop the wood at the area indicated in the picture I posted and call it a day.

Just remember to keep it fun, and build it up how you want to. In the end it's your model, so build it to suit your own tastes. I'm looking forward to seeing your next steps.
Looks great already ! 🙂

Very interesting info, my friend @lgardner!

Looks like a great addition, John (@johnb). I don't think I have ever seen anyone add wood to a biplane before. Should look great, even if you can't see much of it after assembly.

From experience, @johnb, wood decal works much better for this. It's scaled down, while the wood you are using is 1:1.

@johnb interesting stuff! It's all learning. Can't wait to see the clamps come off and hear what you make of it!