When we crossed over at Chiang Khong back in February.
The Thai side said to wait and go over in three groups of not more than four, so we didn't have any hassle on the Lao side.
We waited about 30 to 40 minutes after each group of bikes went over before the next lot proceeded.
A couple of months later when crossing at Tha Li.. No drama what so ever.
The other guys had ridden up from Loei. I rode really early in the morning from CNX.
When crossing over at the Lao side the fellas were finishing off their paper work.
The Lao side was very relaxed and very quiet.. Didn't care about how many bikes and no questions or looks or concerns on either side of the border.
Cheers
Brian