"Premature optimisation is root of evil" +1 for this.
I've left more decapitated Java servlets in my wake doing this than I should care to admit, haha.
You can load images dynamically from blank sprite objects using the "Load image from URL" action. You can dynamically load Text objects using AJAX and JSON.
You can load assets with AJAX too using the "Request project file" or "Request URL" then request an image URL. For instance, on our website (http://50.112.151.9/home) we load the test text and images on the "About" page using JSON AJAX calls. That way it only loads each pages content when that page is visited. But you still need blank sprite containers for all of those objects.
Like this: http://postimg.org/image/kfuv0y92z/
The JSON file that it loads from looks like this:
{
"p1":["This is a paragraph of text for JSON delivery. 1","500","200","2200"],
"p2":["This is a paragraph of text for JSON delivery. 2","500","300","2200"],
"p3":["This is a paragraph of text for JSON delivery. 3","500","400","2200"],
"p4":["This is a paragraph of text for JSON delivery. 4","500","500","2200"],
"p5":["This is a paragraph of text for JSON delivery. 5","500","600","2200"],
"p6":["This is a paragraph of text for JSON delivery. 6","500","700","2200"],
"p7":["This is a paragraph of text for JSON delivery. 7","500","800","2200"],
"img1":["wizard2.gif", "800", "900", "0"],
"img2":["wizard_male.png", "800", "400", "0"],
"img3":["", "0", "0", "0"]
}