Is there a maximum number of pages you can have in any single layout? I was trying to have over 10 pages or page breaks, but it wouldn't let me drag the body down any more. Is this the max ? (10 pages)

yes.

So how do I get around that? Say I need 15 pages?

Actually, it is the length of the layout - 111 inches. This includes all parts.

A slight workaround is to use landscape orientation - this will give you a little more real estate - maybe a 2 column type setup if your data will support it.

The only other workaround is to split your print layout into 2 (or more) layouts and script your print to go to each layout, print it, then go to the next part and print, etc. The down side to this is if you want to save to a file, such as a PDF, the output is split into 2 or more files.