The OP, s wife is non Thai.
Easy for him to enter Thailand visa exempt and obtain the non O here in Thailand or nearby embassy such as Vientiane.
Normally the advice would be to obtain the Non O in home country however NZ costs for this seem ridiculous.
If he doesn't have a Thai bank account then he needs to obtain the non O outside of Thailand.
At some point the wife would need to obtain a Non O (dependant) outside of Thailand.
She is under 50.