@Brandon ***********
As always, thank you for your prompt reply. I am leaning towards not trying to enter by air, not even in Chiang Mai. If denied entry at an airport, it is just a lot of issues (being detained, being put pack on a costly plane of the same carrier and having an ugly stamp in the passport). While at land borders, it is mostly just being turned away / around (ok the cancellation of departure stamp in the country one just came from would also suck to have in ones passport). Also, very few flights to CNX do not go via Bangkoks airports (where most swampy things happen).
As for that VIP service. Was about to make use of it. The advertised 2000 THB sounded reasonable. Up to 5000 baht (as you mentioned), I might have considered it. But I learned, their pricing differs a lot. For people having been in Thailand for more than a year during the past two years (not that there is any legal mentioning of this in any Thai law), they suddenly charge more than 8500 baht for that service. In my opinion that is a bit much of brown envelope money.