Can I get a marriage visa in Thailand through the Savannakhet Laos embassy, and how does it compare to a retirement visa regarding extensions?

I'm a US citizen, married to a Thai national. I'm currently on a 1 year extension of stay (expires March 28th) based on being over 50 years old, and having a monthly income in excess of 65K Baht. Now that the US Embassy has stopped issuing income affidavits, and I have NOT been sending 65K TBH to my Thai bank for the past 12 months, and I do NOT have 800 K TBH in the bank, I will need to change the way I get permission to stay in Thailand. I have had in excess of 400K TBH in a Thai bank for 5 months now. However, my understanding is that it is a pain in the arse to get an extension of stay based on marriage, while in Thailand. That said, I understand that the Thai Embassy in Savannakhet Laos can issue me an actual marriage VISA overnight, without proof of 400K TBH in my Thai bank. I have some questions. First, as a US citizen I know that I need a Visa to enter Laos. Can I buy a Laos visa at the Savannakhet border crossing, and if yes, how much will this cost me? Also, if I get a marriage VISA, does it work the same way as a retirement visa, in that if you leave Thailand a few days before your retirement visa expires, and then return to Thailand before your visa expires, Thai immigration will stamp your passport with an expiration date of one year in the future, basically getting 2 years for the price of 1 year? Any guidance would be greatly helpful.