your correct. I always get that border wrong and don't you still need an ETA at that crossing I know THE FRIENDSHIP BRIDGE in NAKHON PHANOM doesn't do it
not possible, Vietnam has electronic application. Takes to much time. Border run. But in reality they are not going to do anything for 3 days. No stamp just a fine of they wish to. I had over stay for week and immigration officer laughed and said they love making extra money. Paid a small fine no stamp. He said over stay is no serious under 30 days.