My suggestion is that if you are in a party and join a solo gamemode that you should not spawn right next to one another. I feel like spliting up the partied person will effectively but not entirely cut down on the teamers we find in solo gamemodes.
Hate to break it to you, but that's not exactly the point he's trying to get across. I'm pretty sure he knows how to do that anyway by looking at his profile picture. :DIf some players in a party are teaming, they can be reported and banned. They should already know the consequences of teaming.