If you live in the EU and have insurance from an EU based company, you are covered for *ALL* European Union countries. This is for 3rd party cover but all insurance companies should extend this to fully comprehensive when asked.
However Bosnia and Montenegro (as well as Kosovo, Serbia, Macedonia and Albania) are not in the EU.
You are correct, that the insurance purchased at the border is for 3rd party only. This prevents you getting arrested/fined by police or border guards when you try to leave the country.
Sleeping with the bike in your room is quite frankly ridiculous. The Balkans is not the 3rd world, many of the countries are wealthier than recent EU members. Most hotels, hostels and guest houses will be very accommodating as regards security. Many will have locked compounds/courtyards, underground parking or other secure parking nearby.
Many insurance companies will provide a green card for some countries in the Balkans, so you will not need to purchase insurance at the border. You should check with your insurance company, but this will usually mean that they will extend your fully comprehensive cover to those countries.
Originally Posted by michnus
Well it depends if you are from EU. Maybe your insurer at home will cover some EU countries. But as a rule, no insurer will touch a bike or car or moving anything for insurance when doing long distance far away trips. In South Africa our insurance will cover till Malawi for example but not countries above that. Risk is your own.
We met two Pommies in Spain and one guy trashed his bike. His UK insurer covered him for that. Do not think UK insurance will go as far as Balkans and such.
Sleep with bike in room ;)
Also why it is never a good idea doing such trips or round the world trips with new expensive bikes.