I October, I'm going to guess that your main targets will be speckled trout and redfish. Tarpon, copia, spanish macks will have probably gone south for the winter, but I'm not an expert in that area, so I don't know for sure.
If you want to only use one line, I would use the floating line with a fluorocarbon leader. You would be better off with both lines, since you may want to get down deep if the weather is cold.
My choice of flies would be:
Trout flies:
gurglers in chartrues, white and light brown
decievers in cockroach, chartrues/white and black
clousers in chartrues/white, white and brown/white
Redfish flies:
kwans in light brown and dark brown
kwans in light brown and dark brown
kwans in light brown and dark brown
if the kwans don't work, try bendbacks in chartrues/white, brown white and black/red.
clousers and decievers will also work.
Most of the flies I use are in the 1 to 2/0 range. Make sure you have the flies and lines to cover the entire water column. Depending on weather, the fish could be up on shallow flats or in deep holes. Remember trout are top feeders and redfish are bottom feeders.
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