Plays that are written after the plays within them

The obviously very speculative idea that Nabokov’s Pale Fire and Wallace’s Infinite Jest both began as plays-within-plays but without the exterior play, which they then tried retrospectively to build an exterior play (or novel) around.

In Pale Fire‘s case, the play-within-the-play is its extraordinary but perhaps somewhat anachronistic poem; that was great but didn’t work on its own as a poem, so what could he build around to make it work? In Infinite Jest‘s case, it is the experimental films of the genius father that didn’t work as pieces on their own, so what setting could Wallace give them that would make them work?