I doubt you'll have to undergo an 'interrogation'

in Udon. Elsewhere, particularly in tourist areas, checks are made on room occupancy, maybe 'friend's' ID held - particularly at the better hotels???
It might be useful, if you are using the internet, pre-booking or just walking in, to specify a double room - for two occupants. You don't have to name the second person. I did that with an internet booking for fairly good hotel in Patong. No problems for me, but I was aware others had this guy pursuing them to check in early hours of morning. Great! - when your mind's on something else.
