Why do you need a new passport- you haven't done anything wrong. Why not apply for a TR visa while your in Canada, that way, if granted you know your good to go. Then, when you come back after your TR visa expires you can do 2 land border bounces this calendar year.
Yes great advice- poster should come in on Visa Exemption then get his passport renewed here. That's what I'd be doing. When new passport received look at getting METV.
mmm now your staying with a friend in Poipet. Your 1st post said you wanted to enter from Thailand and then turn around and go straight back. Take the bus solo from Ekkami.