There should be no difference in setup for 300FT or 1/4 mile as far as the Flat Panel Antennas except for height off the ground. The farther the distance between antennas, the higher the antennas should be off the ground since the signal spread out more with greater distances.
One thing to check is the orientation of the antennas when mounted. Most high gain antennas have a horizontal orientation and a vertical orientation, that is, how the signal shape 'looks'. The Flat Panel Antennas RaceAmerica sells have three mounting studs on the back of the antennas and a label showing orientation (an arrow to show where up is). When holding the antenna as it would be mounted and viewing the backside, the three studs would be located at upper left, upper right, and lower right with the orientation label in the lower right. No stud in the lower left of the antenna back plate as shown in the photo.

RaceAmerica did find a limited number of antennas shipped from the manufacturer with orientation labels applied incorrectly. This caused some low RF signal levels and was corrected by changing the mounting orientation of the antenna and moving the mounting label to the correct location on the back of the Flat Panel. The best way to ensure proper mounting is to match the mounting stud locations as shown in the photo.
For additional background on RF communications, check out the Technical Article on Wireless Communications on our website at:
*** RIGHT CLICK THE LINK BELOW TO OPEN IN A NEW TAB ***http://www.raceamerica.com/articles/art002.pdf