Using Mesh will reduce performance for clients connected to the AP on far site. P300 is a point to point link which will provide better performance. On Far site, you will anyway have power for the AP so P300 for point to point and an AP(Omni or directional depending upon location, requirement) would work. How much bandwidth you have at AP side and how much is required on far site? you can also consider some other point to point solutions like Ubiquity, Ignitenet etc.