Stuck at border: Taking a Vietnam-registered bike into Thailand at Pakxsan/Bung Kan

[AdamCohn]

Hey all,
I arrived at the Lao/Thai border of Pakxan/Bung Kan today, and tried to cross from Laos to Thailand with my Vietnam-registered Honda. The folks at the Lao side were really helpful and wanted to try and help get me across, but ultimately failed. I'd like some advice on what to do next.
The best I could get from the folks at the border is that I need a Thai Vehicle Passport to be able to take the bike into Thailand. One lady keeps saying that she thinks I can get one at Vien Cheng, but I'd rather not backtrack there unless it is a guarantee. Does anyone know for certain on that?
It is Saturday evening here, and I knew going into this that the boat wouldn't run until Monday (thought I'd chance it though). What do you think the odds are of me successfully passing if I try again on Monday?
My other thought is that if getting a Vehicle Passport is going to be a big hassle, that I will just skip Thailand and go back into Vietnam. I'd really like to explore Thailand though, if possible.
So, if anyone has advice, I'll hang out here in Pakxan until tomorrow morning local time and would love any advice from you folks, if you have any!
Adam