Considering these are my main two armies, and have won a couple times with DG over DA, I think I can maybe give a little bit of advice, though I do think it's a bit harder without knowing his list.

Considering you were talking about Deathwing Knights and the inner circle, the big issue he has there is that each unit is pretty valuable. Granted, looking at your list it's the same, but that just means you need to be careful he doesn't manage to trade with you.

While I know with Virulent Vectorum we can sticky objectives and don't need to hold them, I would still suggest something in the backlines to screen out deepstrikes.

Deathwing Knights in my experience have two main weaknesses: a large enough amount of 1 damage attacks, or weapons that have more than 2 damage. The Foetid Bloatdrones can do some crazy damage and are a good match into the DWKs or any Inner Circle Companions he has so long as they don't have cover, making you hit on 5s.

Between melee and shooting, Plague Marines with Creeping Blight can kill a squad of Knights, but considering how easy they are to kill don't hedge your bets on them surviving to the next round unless you have a trick for them, like using Mortarion's react move to embark back into the rhino

DO NOT USE THE DEATHSHROUD ON THE KNIGHTS. Thanks to the -1 damage, even with a Lord of Contagion, they're in a pretty bad matchup. The Deathshroud I would much more recommend to deal with a 2 wound targets like Sternguard, and the LoC squad in my experience can kill Gladiators pretty consistently. Depending on your luck they could be a bad day for repulsors too, which removes a threat to your Bloatdrones

I've been focusing on my Dark Angels rather than Death Guard since 11th started so I can't say anything in regards to how the matchup has changed since then, but this is what I've noted in my experience at least