Laos (Time to process: 20 minutes)
There is a barriered check-point before the border buildings. Ram the barrier, and stop when you get to the large building on your left. There is a car park behind it if you feel like keeping the road outside uncluttered.
Firstly, the toilets. These are the first part of the building you encounter, and if you require their services in a male, standup sort of way, then be prepared. You'd have more privacy from the world outside if you pee'd on an airport runway.
Ballast reduced, go to the immigration window. This is at the opposite end of the building to the loos.
Retrace towards the loo, and come to a window saying "customs" on it. If you go inside, you'll find it's a store for large sacks. And no matter how much you insist, they will not stamp your Carnet.
Open your ears, and home in on the karaoke. Follow it to its source, and enter the office. You are now occupying space in the inner sanctum, home to the chief of the whole Laos border-show. Fret not. Have a song, then he'll take you out to a window next to the one marked "customs", towards the immigration window. This unmarked window has bodies inside just waiting to pounce on passing unsuspecting Carnet documents.
Thailand (Time to process: 20 minutes)
This side of the border is far less grand in construction than the Laotian side.
The first office to visit is the customs office. As you cross the border, you enter a small compound and can travel no further. Abandon the truck and enter the customs office on the left. It's a small office, packed with smiling faces.
They complete the Carnet, and DO NOT ISSUE ANY COMPUTERISED THAI-CUSTOMS DOCUMENTS. (To date, it was only the Sadao border crossing from Malaysia which issued the computerised Thai- customs documents.)
Then exit the office through the back door. Wander into the market to your right, buy your lunch and some tacky plastic toys,and then emerge at the other side of the market. You'll have the immigration office right in front of you.
When finished here, retrace your steps through the market.
There are no checks on documents as you exit the customs compound into Thailand. But don't forget to drive on the left-hand side of the road from now on.