Old Endermite Spawner doesn't work now, need a new design. (Server with plugins, so not "full" vanil

We had an old design where endermites fell onto cobblestone walls(P.S. we have endermite spawners) and then their loot would drop beteween the walls and into water to go to chests - now we need a new design because recently the server added mob stacking and only one mob dies, so they fall into our loot system. Aka the farm is really inefficient now. Came to this subreddit to ask for help with potential new designs, as we need one that will kill stacked endermites decently fast and give us the loot. I've been pondering on it for a while with no luck, so have at it!

P.S. I had to post this twice, when looking at the tags, I thought in examples it was saying we **should** do [Java 1.15.2] until my post got deleted and I had to relook at it. (Totally not facepalming myself to death rn)
https://myip.kim/ https://birthdaywishes.onl/ https://elecpay.in/tneb/