I've done Elvaan and Hume with a very small amount of people before. We had about 4 or 5 people, one was dual boxing Nin and Rdm, another Rdm, Thf, Cor and my memory is fuzzy on the last job but I think it was Smn.
Most groups will already have a Thf in them for TH alone, but they offer far more utility for this fight simply because they can clear entire rooms + hallways of Fomors and the Minotaurs at the intersections using Flee and Hide.
****For those not familiar with Hide's mechanics, you need to make sure the aggro'd mobs are far enough away from their spawn areas before using Hide, or they will NOT depop****Simply start in the back of whatever room you're looking to pop the swift belt NM in, drop sneak and pop flee(bring your af boots if you have them, as they do work in level capped zones), make sure to grab every fomor in the room and as many of the mobs outside of it down the path I marked in green on the map below(even the minotaur if you're able to). Take everything as far from their spawn area as possible to the end of the arrow, and if you did it correctly, it should despawn all mobs on the way back to your room and anything that was inside of it potentially saving your group a ton of time and heartache fighting everything and risking links/death.

The only room I found I couldn't completely despawn sometimes was the Taru(Lobais) room, one of the Blms would occasionally run all the way back to his room for some odd reason despite being way out of the range of it. And with the Hume room(Balor), there's mostly ranged mobs in the hallway outside of it, I think it was a RNG and BRD. For Hume(Balor) you want to run the opposite direction marked in blue on the map and stop in the corner next to the door just shy of the maze entrance wait for the mobs from the room to get into the hallway then pop Hide. This would leave me super low HP sometimes since most of them were ranged mobs, so you'll likely require someone who can heal/sneak you to get back to the room and avoid HP aggro from the nearby skeletons and the Rng/Brd fomors in the hallway. Everything in the room should despawn if done correctly though.
Sounds complicated, but really isn't once you know what you're doing, and it saves you a ton of time provided people listen and it's done correctly.
I did the paint job in like a minute, so sorry if it looks like shit.