I'm more typically accustomed to a severe and frankly tiresome degree of snark on such topics, having had more than half a lifetime more or less of such now by virtue of living outside the South but retaining a strong Mississippi accent in speech. Sometimes I forget I don't type with one, and read with insufficient charity in consequence.
That said, I do think your understanding may be usefully clarified for a bit of further analysis of the figure. "Might could" means "may be able to", and is constructed accordingly. No one would say "be able to may", and "could might" rings likewise false. The same meaning constructed from two modal verbs yields "could maybe," which is something I've often both heard and said.
I'd also note that there are lots of common English vernacular constructions, especially in more distinct dialects such as AAVE and my own Southern American English, which rarely appear in dictionaries. While we're burdened with no formal equivalent of l'Academie at least, there is a strong strain of prescriptivism wrapped around the loosely defined but quite real American system of social class, and relatively disfavored dialects such as both I just named consequently come in for a great deal of "that's not real English," with their figures often relegated to lexicons despite possessing as clear and consistent an internal grammar as any other English dialect - at least until they're adopted into mesolect, as with "y'all" and, thanks to Twitter putting a turbocharger on the appropriation of linguistic culture, roughly half of AAVE - in both cases, quite poorly. Comparing AAVE and SAE is always fraught given the history, even if that history needs to be a little esoteric to appreciate that a planter would've spoken quite differently from me, and thought me white trash besides. But I think it's fair to say both dialects about equally honor the music of language, albeit in somewhat different ways; meanwhile, the dialect of American mass culture insists on the tinniest of ears, and that above all else is what a modern American English dictionary seeks to document and formulate.
This isn't precisely to impugn the compilers of dictionaries, who do mostly good work despite my differences with their approach. It is to say it's worth knowing that for a lot of vernacular especially among disfavored dialects, a strong intuitive sense of English linguistics and the history of the language will often yield a clearer understanding.
That said, I do think your understanding may be usefully clarified for a bit of further analysis of the figure. "Might could" means "may be able to", and is constructed accordingly. No one would say "be able to may", and "could might" rings likewise false. The same meaning constructed from two modal verbs yields "could maybe," which is something I've often both heard and said.
I'd also note that there are lots of common English vernacular constructions, especially in more distinct dialects such as AAVE and my own Southern American English, which rarely appear in dictionaries. While we're burdened with no formal equivalent of l'Academie at least, there is a strong strain of prescriptivism wrapped around the loosely defined but quite real American system of social class, and relatively disfavored dialects such as both I just named consequently come in for a great deal of "that's not real English," with their figures often relegated to lexicons despite possessing as clear and consistent an internal grammar as any other English dialect - at least until they're adopted into mesolect, as with "y'all" and, thanks to Twitter putting a turbocharger on the appropriation of linguistic culture, roughly half of AAVE - in both cases, quite poorly. Comparing AAVE and SAE is always fraught given the history, even if that history needs to be a little esoteric to appreciate that a planter would've spoken quite differently from me, and thought me white trash besides. But I think it's fair to say both dialects about equally honor the music of language, albeit in somewhat different ways; meanwhile, the dialect of American mass culture insists on the tinniest of ears, and that above all else is what a modern American English dictionary seeks to document and formulate.
This isn't precisely to impugn the compilers of dictionaries, who do mostly good work despite my differences with their approach. It is to say it's worth knowing that for a lot of vernacular especially among disfavored dialects, a strong intuitive sense of English linguistics and the history of the language will often yield a clearer understanding.