There have always been either visa exempt entries and for a few countries a visa on arrival. If you mention your passport country then you can get accurate advice.
That part is about how many people are having visas issued, not about seats. Single is fine for what you want, but you will certainly need your wife to attend with you.
You can get a visa on arrival (USD40) or you can use an e-visa (USD50) at that crossing. There were some reports recently that at some crossings they were insisting on 1 or 2 nights in Laos before return, maybe someone will confirm if that applies here.