I'm reading that suggestion as saying that all _must_ (by law), but not all of them _realise_ they must, so prod 'em. I've just pointed my own insurer (a Swinton brand) to that page, and asked them to confirm that they do. They're currently refusing all Balkan countries bar RO/BG (EU) and HR (Green Card), hence me finding this thread, from a campsite in Puglia, heading towards the boat for Albania!

I'll let you all know what we find when we get to the various borders, if we decide that it's not all too much of a headache. In the meantime, I'm also awaiting a reply from another UK broker (Herts Insurance) who seem to offer short-term travellers policies.
https://www.hertsinsurance.com/walkabout.php
Anybody any experience with them or others?

<edit: Update - Forget them, they'll only cover Morocco/Tunisia/Turkey/Croatia + EU>

Because we don't know how much time we'll want to spend in which countries, it'd be preferable for us to not have to worry about the borders, and get a single policy that covers all. I can definitely confirm the bit about other EU countries having no such issues - our Austrian neighbours at this site were utterly bewildered that we should even need to think about it, and checked their own (standard issue) Green Card. Only a couple of "definitely dodgies" were crossed out. Iran, f'rinstance. Can't think why. We're just back from Tunisia - we bought local cover there, from a random high-st broker in Tunis, three months for ~€100. Cheers, and may your travels be good 'uns.

<edit: Updates beyond these points are the reality as we cross borders>
Albania - As we returned to the van on the car deck of the Brindisi-Vlora ferry, ready to disembark at 7am on a Sunday, we were approached by a man who asked (in English, after a few other attempts) if we had insurance. 15 days - €27, 30 days - €51. Official looking sheet of A4, badly scrawled details. 30 day premium given on sheet as €44... As we exited the boat, then port, there were several other similar vendors and an office branded with the same logo.

Macedonia - The southern Lake Ohrid road crossing (Tushemisht) does NOT have any insurance sales facility - and the border guards WILL ask for your Green Card. If you don't have one, you WILL be refused entry. Don't ask how we know this... The northern Lake Ohrid road crossing (Qafë Thanë) does have, just on the inside of the border. You'll need to leave your passports with the police, park between police & customs, and walk through. €50 for 15 days. Euro or Macedonian Denar cash only. No Albanian Lek, no plastic. There is no cashpoint here to get Denars.

Montenegro - The Vladimir/Sukobin border crossing west of Lake Shkodra accepted our SRB (Montenegro included) green card without any question, despite it having been issued in May 2012 according to the pre-Feb 2012 country list, and being a colour-print of an emailed PDF rather than an original. There didn't appear to be an insurance sales office on the Montenegrin side of the border, but there were several for Albania on that side.

Croatia - We have a green card. The border crossing south of Dubrovnik was utterly painless. If you do not have a green card, there was a phone number on a piece of paper in the customs hut window. No cash machines.

Bosnia - The border crossing NW of Bihac was incredibly laid back. Croatian customs wanted to see our V5 on leaving, but the Bosnians weren't bothered on entering. We had no green card, and had to ask about insurance. They looked surprised, but pointed us to the freight management company hut just inside the border. We were pointed from office to office until we found somebody who would sell us insurance. He could only offer 16 days cover. Initially, he asked for €122 for motorhome price. We thought this very high, and showed him our old VW. He then charged us €32 (58KM) car price, without any further discussion or argument. Euro cash, Bosnian KM (no cash machine) or Croatian Kuna (at normal exchange rate, no premium) all acceptable.

We have heard of others who were quoted, at a different border and for a bigger motorhome, €75/14 days or €55/5 days. We have also heard of somebody paying €25/3 days for a car. I think they make it up as they go along...