Sure your way is very near to a solution, but it doesn’t eliminate the need for a page-by-page correction.
No it’s not. There will always be one more situation where the framework falls short of one’s expectation You can only hope that the wish list makes it to the todo list...
For this sort of "one-time-structural-changes" I wouldn’t try to code a snippet/@eval thingie that I’d only use once in a lifetime.
I would go to myphpadmin.