Can I exit Thailand via Nong Khai border with two passports and obtain a new visa on arrival?

I went through the search function of this group and found posts saying opposite things, so here I am with my situation:

My New passport is completely empty. I got it a few weeks ago.

The last entry on my old passport is a 60 days visa exempt entry, of which I've extended by 30 days, and then by 60 days (visiting Thai wife).

My 60 days will expired on October 5. The immigration office in which I did the 60 days extension is far from where I am, so I'm not going back there to transfer extension (I don't think i need to anyways?).

My plan was to leave via Nong Khai border by showing both passports. So they will void/stamp the old passport, and then on the Laos side I'll do the visa on arrival in new passport. *I will come back by air using safe entry*.

But then, searching the group, I found posts saying conflicting things. My understanding is that since my last entry is visa exempt, I can just do what I said above. But if I was on a longer term visa, I would have to leave by air so that they transfer from old to new passport (something they can't do at border).

Am I correct or missing something?

Thank!