Go local
I think you will find it an advantage to try local crafters in Sarasota or Bradenton. That way you can try out samples of the various densities and types of foam filler, handle and choose colors or patterns from samples of the various kinds of cover material, and decide with the builder what kind of retainer system would work best for youir needs. You can also choose what size to be made, and the number. There's an advantage for example to having a greater number of smaller cushions and backrests because they can be used in more ways, and stow more easily.I still had my shop in Bradenton I'd do them for you!