Trousers for dinner at upper end restaurants ?

When you travel to Cambodia by river where do they check your passport, on the boat or on arrival in Phnom Penh.
Thanks

I presume you are going from Vietnam to Cambodia. When I did it a few years ago, we had to get off the boat and go through customs/immigration whatever at the border. I had my Cambodian visa but some people were getting their visas at the border. Don't quote me on that as things may have changed. I'm sure you'll still have to go through the formalities at the border though.

Re trousers at upper end restaurants - I suspect so but I don't usually eat upmarket. More a street food person myself. I'm sure I wore shorts to Cuisine Wat Danart last year and the food was beautiful. (Highly recommended)

The top restaurant in Hanoi, at the Metropole, will require jacket and tie plus pants obviously. At night in most restaurant it's normal for people to wear trousers and not shorts.

Agents boarded our boat at the border and checked passports and visas as a group.

The river boarder crossing is a short distance from Chau Doc (Vietnam) and known as Vinh Xuong / Kaam Samnor river boarder post. Cambodia passports can be obtained here for $20 US.

The boat crew will help you and the officials here are quite helpful and there are no scams

Be sure to have a passport size photo.

I already have the visa's.
Already have a booking at Cuisine Wat Danart.

Enjoy Cambodia and Cuisine Wat Danart. As Scotters says, there are no scams at the Vietnam/Cambbodian border.

I'm looking forward to being back in Siem Reap in July.

there is a custom there to check before arriving to Phnom Penh.
But It wont be long.