The latest two volumes of Martin's Song of Ice and Fire have been poorly received compared to the series' earlier books. What's interesting here is that Martin's original plan did not include these books. Rather, these books were a solution to a problem Martin had:
The fourth book, tentatively titled A Dance with Dragons, was to focus on Daenerys Targaryen's return to Westeros and the conflicts that creates. Martin wanted to set this story five years after A Storm of Swords so that the younger characters could grow older and the dragons grow larger. [...] A long prologue was to establish what had happened in the meantime, initially just as one chapter of Aeron Damphair on the Iron Islands at the Kingsmoot. Since the events in Dorne and the Iron Islands were to have an impact on the book, Martin eventually expanded the Kingsmoot events to be told from three new viewpoints since the existing POV characters were not present in Dorne and the Iron Islands.
In 2001, Martin was still optimistic that the fourth installment might be released in the last quarter of 2002. However, the five-year gap did not work for all characters during writing. On one hand, Martin was unsatisfied with covering the events during the gap solely through flashbacks and internal retrospection. On the other hand, it was implausible to have nothing happening for five years. After working on the book for about a year, Martin realized he needed an additional interim book, which he called A Feast for Crows. The book would pick up the story immediately after the third book, and Martin scrapped the idea of a five-year gap. The material of the 250-page prologue for the beginning of A Feast for Crows was mixed in as new viewpoint characters from Dorne and the Iron Islands.
But fan reaction suggests this solution was a poor one, resulting in stretched-out books whose object was to impart key information and to "keep track" of characters who weren't moving as far or doing as much as those of the earlier volumes.
Taking in good faith Martin's descriptions of the difficulties he had with the five-year gap, how else might Martin have solved these difficulties?
I am less interested in how Feast and Dance might have been condensed or abbreviated (that would be an editing question). What I'd like is suggestions for plot/story structures that might have been more appropriate to Martin's purposes. In other words, given that Martin had these difficulties and considered an additional piece necessary - what would have been a better format and structure for such a piece?