do I have to set it up with separate RGB LEDs and daisy chain them?
That's exactly, what the string of Neopixels, that you linked, is: Separate WS2801 RGB LED chips, which are daisy chained together. Since the distance of the LEDs on the string is not 4-5 feet, you cannot use the string directly.
You can either cut the string and extent the cables, as you need to. Or you can buy single LEDs and use completely your own cables. That's up to you; technically it is completely the same.
But since 80 LEDs, each 4 feet apart, will give you about 100m/330feet, you get a problem with the resistance of the wire. First about power supply:
You whole strip would need up to 4.8A of power, with every pixel at full white. You need to transport that current from your source, down to the very last LED. Make sure, that the used wire has very low resistance and is rated for such a current. If the resistance is to high, you will loose voltage over every meter of the cable and the last LEDs might be off color or not working.
I think the signal lines will be fine despite the distance, since every LED outputs them again to the next LED, so the signal should be kind of refined on every LED (though I don't know, how the WS2801 chips work internally).