This is so cool. It's a stab in the dark, but I totally think you hit the essence of what Luffy's mom would be like.

Absolutely awesome and strong and protective and willing to give her life for her son - but not without fighting for it, first!

I'm imagining this letter reaching Dragon, and... breaking him, in some small way. And Luffy becomes even more precious to him, because it's all he's got left of the woman he loved - but he can't even let his son know he exists. Owww.

Gorgeous!