Change of plan?

Just heard that Laos are refusing to allow foreigners like me into their country riding motobikes with Vietnamese plates.  That messes things up.  I will try it on at the border and see if a bribe helps.  If not, I will have to think again.  Maybe head up further north in the mountains then back to the coast to Hoi An.  Had hoped to spend Christmas in Luang Prabang.