Set trust depth to 0 and explicitly add all users you want on your trust network.
When the changes happened in January I also thought we might want separate lists for users whose trust scores we want to see, users whom we want in our trust network, users to "vote" for in DT1 election... but that's not the intent of the trust system, is it? We should add users whose judgement we trust and the other stuff is just sugar, mostly to make it easier for newbies to find their way around. More complexity creates more room for manipulation and we definitely need less of that.
That was my dilemma, there are folks who's reviews I would like to see, but not necessarily give them my vote for DT1.
You can add users to an alt account, then add that alt account to your Trust list. This way, you trust them one level less deep.
I haven't used this option yet though.
I agree the current trust system is complicated enough already, if not too complicated. Promoting custom Trust lists is more important now. I've suggested a big banner like the April Fool joke before, that had a lot of response in just one day.
I thought of this solution, and even created
an alt for that purpose, but I have not implemented it yet.