Can't guarantee I'll be there, but just in case, I'll stop eating from today.
It seems you're right - people are reporting a near 250 mile range, so with basic hypermiling you should be able to make 400 km. Don't trust the "half spent" fuel gauge though, my gauge is halfway at 200 km and the other half just drops in a 100 km.
If you really want to test your range strap a fuel can on the back and keep going till the bike stops.
PS: I missed the entertainment of you trying to back your bike out. Did it make it through alive?