When I did my RAF Boston and Hudson, I did some research into export paint. I never found anything that indicated the interiors were different coming off the production line. The Hudson grey green color was what Lockheed used for their planes in general and is seen also in USN Venturas. Douglas used an interior green color that had a distinct olive drab look to it. You can see it in the color publicity photos taken at the factory. Not sure of the Bostons made by Boeing
I thought the Trumpeter kit had exaggerated fabric effect. I put down two layers of primer and sanded the wings and tail planes lightly until the plastic structure started to show through. problem solved.
When I did my night fighter Defiant I used masks and painted the codes. I have a stencil for RAF codes that I used. If you have to make masks from scratch it is easier to pick a squadron with codes that have more straight edge letters like T or L.