Have you tried the Strathmore 500 series drawing paper?
It's about half the weight of Platine and initial tests have led to some really striking results for me. Much more detail than Platine (I also print 5x7).
I was testing it with fumes silica and getting mixed results but it was the silica causing the occasional streaking I am sure.
I intend to try the Strathmore 300 series plate finish drawing paper as well which looks to have the same surface but is heavier. I'm hopeful the papers chemistry is the same.
Attached is a crappy iPhone pic of the tested image