Google Docs - Custom Page Height

gd_set_dimensions.js

/* Set arbitary dimensions for any google doc. Useful for avoiding the soft-page-break dotted line and table breaks */ 
function myFunction(){
    var doc = DocumentApp.openByUrl("YOUR-DOC-URL-GOES-HERE");
    var body = doc.getBody();
    var pointsInInch = 72;
    body.setPageHeight(40 * pointsInInch);   // 11 default
    body.setPageWidth(8.5 * pointsInInch);   // 8.5 default
  }