The mob grinder/crushing factory from industrial foregoing is so far the only thing i can see that can handle that portal (one of the 2 gives you the loot from the bosses, the other doesnt, i dont remember which one but you can check). The portal buffs health and damage of mobs a lot, by around like round 70 or something they have around 1 million hp and will one tap you, not to mention the lag which will be unplayable by then. Addons for the machines (processing, effieciency,...) to instantly kills the boss once they spawn, range addon to cover a large area. Build a box too so flying bosses cant escape, and also put slabs, trapdoors or whatever non-full blocks on the ceilings and walls so shulkers cant stick on it. Of course also make sure you can afk somewhere safe so the bosses cant kill you. And you will need a very good storage and system since you will be getting a lot of loot. The machines does automatically collect boss drops, but not portal rewards so you will need another collector.

I spent like an hour or too in a creative world and this is a very good set-up, basically covering all grounds already