do you have a marriage certificate, such as Kor Ror 2 or Kor Ror 22? Then, you don't need your wife to get a marriage visa. Have her send you a copy of her Thai ID card, blue ink signed, and a copy of her tabian baan, also blue ink signed; then fly to Vientiane or Ho Chi Minh, take a few thousands baht along if you go Vientiane, USD if you go to HCMC. You will get a 90 days marriage Visa in
AKA TM8. Pay 1000 baht for single re-entry or 3800 for multi (be informed that some immigration offices would also require TM30). If you don't apply for a TM8 then your visa and extension will be void as soon as you cross the border
Photocopies of old passport picture and visa pages, photocopies of new passport picture page. Letter from embassy. Some immigration offices might require a copy of TM30 as well.