Question: picking a master page based on content

[KMickle]

I have a somewhat deep SILE-internal question, but not apt enough to answer it at this time. Any help would be appreciated.

Let us assume I have some material and several different options for the master page. May I try typesetting into all of these pages and then choose one based on some criteria like badness?

The way I see it, here is how it might work:

1. The current typesetting context (everything that has been output so far) is saved;
2. The first master page is selected;
3. Per-paragraph hooks are registered to see and remember how bad things go;
4. The output is reset, and if there is another master page option, select it and go to step 3;
5. The best master page is chosen, and the real typesetting resumes with the "best" master page template.

How wrong is this vision? May this be implemented with reasonable effort? Is there a package for that already? Have I missed something essential?