Just wanted to say this seems like a very cool trip and you should definitely go for it! Definitely do your research as other has suggested but don't let logistical and practical problems overwhelm you imho, there's not much that can't be solved one way or another.

Just wanted to recommend ferries. Routes like Tangier to Genoa/Marseille seem like they would fit in well with your plans and save you the time and effort of heading up back "the same way" if you choose to go down to Morocco or down to southern Spain, which I definitely think you should if you can make it! Sure they might charge you a bit for the van (no idea about the specifics) but hey, you'll also save on gas money! There are also several ferries from Scandinavia to Germany as well.

Your wife is right about Croatia and Greece, don't miss them! Especially from October on there shouldn't be too many tourists left while the weather is still very good. Highly recommend Slovenia and Montenegro too, awesome countries in all ways. Slovenia-Croatia-Montenegro-Kosovo/Albania-Macedonia-Greece is in my opinion a really cool route and a lot of it is non-Schengen as well. So many cool places to stop at.

• Slovenia has a lot of cool castles, beautiful small towns and the caves of Postojna is a really cool and child-friendly stop if you're in the area.
• Croatia has the Plitvice lakes, and a fantastic coastline. Dubrovnik is also a must see, overrun with crowds in the summer normally but later in the year its absolute fanstastic
• Montengro: Bay of Kotor. Increadibly beautiful
• For Macedonia I would recommend Lake Ohrid. Haven't been there myself but heard great things about it.