Alright sounds good and I love the last ideaIt essentially can be by using the SDcafiine plugin, and putting the file here in each DS game's respective place in their sdcafiine folder. Though I prefer just making it permanent via ftp. That way it can forever work on any cfw that way without any plugin needed.
Frankly what might make the most sense is if someone made an app like the theme installer so that you could patch any DS game you have installed with these additional layouts via a simple homebrew app.