.
Have you tried pouring a small amount on the support and coating with a copper pipe? You end up with a nice, smooth surface. Smooth surfaces seem to work better.
I size my papers with acrylic medium (hot dog roller). They have a slightly rough surface when dry, but when I zap it in a dry mount pres,. I end up with a very nice, smooth surface.
Wouldn't copper mark the paper? Maybe a puddle pusher or even a wine bottle or a Voss water bottle would do the job.
Your post got me to thinking though. I was getting more and more micro-blisters and loss of sharpness in my image (see attached pic) so there was definitely something wrong with my sizing. I also got lots of tiny shiny spots in the dried sizing, which I accounted for the blistering or highlight damage.
In absence of a dry mount press, I tried ironing the dry, sized paper at a low setting, putting a sheet of photocopy paper in between. I just pulled a print from the dev bath and it looks so much better! It's a bit early to say I found a solution, but that might be a big improvement.
Thanks,
gm