If range is a problem, you can just have multiple 5ghz access points spread out over the area, and they'll still cause less interference than a single 2.4ghz.
Really, don't overcomplicate this. The only downside to 5ghz is having adapters that support it imo. With 2.4ghz, you are likely forced to use 20mhz channel width, which destroys your wireless speeds. Using 40 mhz channel width on 2.4ghz will generally cause interference with your neighbors and vice versa.