I don't think you want to run that many miners on wifi connections. wifi is really not the solution for any sizable deployment.

You mentioned your restrictions with distance, so how about this:
1. Setup WIFI router A at your internet access point
2. Setup WIFI router B to be the common access point for all your miners in your mining area
3. Setup router B to be a hotspot or repeater of A
4. If distance between A and B is an issue, throw a few boosters / repeaters in between to cover your dead spots. They are cheap from BestBuy, etc.

This reduces the number of connections to your WIFI broadcasting signals and technically should allow your WIFI router to better prioritize its traffic.