Is there a way to increase the boss spawns on a given map?

Is there a way to increase boss spawn on a given map? I have done about 50 raids by now and the only time a boss spawed was the first raid on customs and haven't seen a boss since.

Thanks for your reply. I have seen this mod before but it only had an r7 version, but now realised it had been updated to 1.0.0.