It depends on just how clear your line of sight actually is, and perhaps on what kind of weather you experience.
If you can stand where one antenna is to be located and, using10x binoculars, see the point where the distant antenna is to be located, that's what it takes. Any trees, buildings, hills, or whatever that get in the way will reduce your chances of it working directly in proportion to just how much in the way they are.
The problem with a 4-5 mile path is that losses are fairly high anyway, so you don't have much room for "margin".
"Margin" can be defined as "Shit Happens". You'll get path fades for certain types of weather conditions (heavy snow,*really* heavy rain), atmospherics (inversion layers can reflect radio signals), trees that are bushier in the summer, and odd things like reflections from large vehicles temporarily in the area between the antennas.
Essentially, if you set up a link that is just 5 dB above the threshold, there will be times when the path has 10 dB more loss, and your link will fail.
Higher gain antennas, with narrower beam width, are good. A dish antenna is particularly good because it has fewer sidelobes than many other types.
Also, in the US you can use some fairly high power transmitters for wireless and still be quite legal. (Consider that the first microwave I ever worked on cost more than $100,000 per site; while by the 1970's it could be done for merely $10,000! And today you can put in something with even better bandwidth for less that $500 per site.) I saw an ad for a 1 watt transmit amplifier and an 18 dB gain receive pre-amp all in one unit for $200. A wifi AP, a 1 watt amplifier, a dish antenna (and buy the best semi-rigid 1/2 inch coax you can to connect to the antenna, and keep it as short as possible), and it should work like a charm.
Note that commercial microwave links that cover distances like30 miles use 1 to 2 watts of power but use low loss waveguide rather than coax to connect to the antenna. If you can keep the feed line short enough, with a 1 watt transmitter you have the equivalent.
If you do have line of sight, that is.