I go down regularly but speak fluent Thai and know people there.
Travel between cities after it is dark is a no-go. There are hardly any foreigners so you will be quite special. It should be okay as long as you have a good accommodation and keep to sightseeing. But if possible have a number of a Thai person you can call and they can translate if you find yourself in a unforseen situation (not much english there). Also I would not wonder off or take adventure trips into unknown areas ...
In Chiang Mai and in another area I could just keep the slip. When I moved to the other province I would just change the paper and keep the other one somewhere else. I had never had any problem with that so far