have you tried these? I think they call them "Weighted Bench Pulls." They're great with dumbbells too.
I love this pic, not only is the bench great, but it's neat how her elbows are out so probably targets the upper back more when they're higher like that.
One thing I'm wondering about why we do these on incline benches as opposed to flat: could it be that most flat benches are just too low to the ground to fully stretch out our arms? I think a lot of benches are just designed for pressing and for safety reasons they keep them low, but for doing chest-supported rows, I think we want high benches to fully extend the arms.
Even that guy would have problems with larger plates though I think. Since you could get really strong at this movements (even though it's designed to limit lat involvement), I could see people eventually being able to row a couple 45s this way. But I think 45s would hit the ground so you'd need a reeeeally high bench.