Hi Stefano! Congrats on your bag! Navy is an amazing color. Sorry, I can't help on the "oblique" stripes. Not quite sure what that is, but others may be able to chime in. The vertical stripes are so striking. This is what I would do, and I LOVE the color combo of red and white. Very classy. I cannot wait for your reveal and am so excited for you.
Have you had a chance to look through the threads of all of the gorgeous St. Louis bags to get an idea of how the stripes will look? You will really enjoy doing this. It is a real treat. I know a few have had the GOYARD logo customized on their bags. You can find their pics on some of the threads in this forum. Perhaps you can send them a message to ask about the price. Hope this helps.