Surety of supply - you may have a point. After all Belgium is a well known third world country - I bet diesel is rationed too (only available when there's an 'R' in the month).
FFS: As I said earlier; just take a can (or 2) of red across and when you get there dump it in your main fuel tank. There should be plenty of room by the time you arrive. It's not like the Douane is waiting to check every yacht's tank as soon as it arrives.