That was probably Winnie Views: How To Move to Florida in 1 Hour in which Lynn describes how she flew to FL in 2015 to set up this state as her residence in order to get a good ACA health insurance plan. Then it seems she flew back to Illinois never to return. About a year later in 2016 the Department of Health & Human Services issued a Residence FAQ (PDF) for the ACA to prevent what Lynn and others were doing -- changing or appearing to change residency in order to get better or cheaper ACA health insurance. It's hard to get mad at Lynn because she died a few years later in 2018.
Nevertheless, a number of full time RVers think it's ok to complete a residency "checklist" (get a new address, register vehicles in state, etc) without actually residing in the state. Even Escapee's in its recent (August 2019) The Ultimate Guide to Establishing Your Domicile as an RVer says "it isn’t enough to choose a new state, go there for a week, fill out the paper work and then take off with no intention of returning to your new state of domicile". For those of you who still think "checklists" are enough, read the Sanchez Case.
It's also not a good idea to purchase health insurance in a place you never reside.
OP, some final thoughts for you . . .
First, I admire your candor. You're new and asked fundamental questions that got to the heart of establishing a domicile as a full time RVer. However, it's never a good idea to say in a public forum as you did "We have no plans to reside anywhere" but go on to say that you "want to establish residency in a state that has better insurance options".
Finally, I think the best answer to your concerns came from Kirk W -- make sure to check out those links he listed.