Make raids harder when defending a village with more people

I'm playing survival (1.15.2) for a while now. And I pretty much have the best gear you can get. I would say raids are balanced if you do them alone. But this survival is on a server, and if I team up with friends, so for example I do a raid with 4 people. I feel like the raids are not that hard, and too short. They are too easy. 

In my view it's a good idea to have the raid difficulty depending on how many players are doing this raid. The more players you have, the more waves you have. For example make every extra player in the raid causing the raid to have one extra wave. In addition, it would be cool if these extra waves contain more enemies, more pillagers, evokers, more illagers on ravagers, etcetera. Perhaps it's a cool feature to make the raid enemies come from different sides at a dedicated wave level, of course in groups.

Now, I'm not a tester so I don't know if ''make every extra player in the raid causing the raid to have one extra wave plus add more enemies in these extra waves'' is balanced. But it's just an idea.

So what does count as 'doing a raid', when does a player join a raid?

I don't know how this mechanic works, but it will work the same as players get the Hero of the Village effect. And otherwise, a player joins a raid when the bar on the top of your screen occurs titled 'raid'. 

I believe this suggsetion will get raids much more fun to do, especially when you're with an entire army.