Its difficult to through the code. Let me explain it. Suppose you want 3 menu items in left then 1 logo and then another 3 menu items. So you have 6 page. Its pretty easy to count that. But what if you have 6 subpages for menu 1. 2 for menu 2 and so on. So you cannot calculate in which position it should be placed.

So I'd suggest, to create a page for that logo. Then use the nav property that says don't link in nav, so it won't click able. Now put a class in that page and in css add that class background image.

Rony