It's not a good idea to just say such and such says this, just because they're really good. So I'll make a statement and then try to back it up a bit more. So some very incredible grapplers like Marcelo Garcia and the Mendes Bros don't like to play half guard because against bigger opponents it;s very easy to get smashed and a lot of weight put on you, since it's harder to maintain distance between you and them. Your better half guard players tend to be people that don't do absolute divisions or if they do, are bigger, like Bernardo Faria or Lucas Leite. With larger cores they can stand to have weight put on them without it crumbling their guard.
That said, I still play a lot of deep half on bigger people. I just try to play it in a way where I can use either my inside leg or outside leg as a butterfly hook under their trapped leg (Jeff Glover and Sim Go are masters at this) or I play the Waiter style deep half. That waiter style can be used to keep their weight off of you a bit and is great for sweeping or taking the back. If you look up waiter sweep you'll see exactly what I mean.
I would recommend checking out any Jeff Glover's deep half stuff. He's probably had the best success with getting half guard to work against much larger opponents. Jeff Glover, Bernardio Faria and Ryan Hall all have great instructionals on the deep half.
I've never been great at regular half guard on bigger people so I don't really play it. I like lockdown or deep half.

Originally Posted by
David Rosado
Any half guard that puts you under them. Deep half. X guard and single leg x. You keep their weight off of you and keep them off balance. The downside is that it takes a lot of practice to get good at them.
Great post. People don't think about it this way but the x guard is basically deep half guard but they're on one or both feet instead of down on their knee/s. In either case you are directly under their base and basically just making yourself an unstable platform in order to keep them off balance and sweep them.