I went through the exact same process for my dad last summer. After a lot of digging, I went with https://goshentinyhomes.com/ because they had experience building ADA-friendly layouts and knew Jacksonville permitting inside and out. They helped us design a unit that was flat-entry, with wider halls and even included a walk-in shower with rails. They managed all the approvals, including setbacks and utility permissions. They even explained the inspection schedule and helped prep for each one. Have you already had a survey done on your lot, or are you still early in the planning phase?