The fact that you don’t have a permanent home should not affect your eligibility in State B as long as you are currently residing there and intend to remain there.
In HealthCare.gov states, to qualify for a special enrollment due to a permanent move, you must have had been enrolled in other minimum essential coverage, such as under a job-based health plan, another Marketplace plan, or Medicaid. You must have been enrolled in such coverage for at least one day during the 60-day period leading up to your move. There are exceptions to this rule for people moving from another country and for American Indians and Alaska Natives.
In addition, in HealthCare.gov states, the Marketplace will not make this special enrollment period available to you until you have actually moved.
Contact your state Marketplace for more information about the permanent move special enrollment period.
Browse more questions in the Marketplace Eligibility section.