Mike - I have used wetpack for my tests done a ways back with my R9.
here and
and here . Some post expansion pics are there.
I did not have any fabric as an initial barrier, as I was mostly doing just a simple assessment/comparison of different bullet's performances from that gun - probably should have in retrospect.
Having the paper totally soaked means you get some hydraulic effect and so expansion is much assisted - tho of course it is only the vaguest approximation to tissue!
I would expect that your glossy paper will still saturate eventually - and my prep'ing method (Steven Camp does much same) - is to bundle up the material (newsprint) and leave immersed in water a full 24 hours. Do not bind too tight tho as whole deal swells and will break cord.
Take out and leave to drain for maybe 30 minutes (it gets heavy!) - wrap in polythene sheet and transport to range and use.
I usually shoot from about 6 feet distance and try and mark front surface with marker pen to give me identifiable zones for reference. Having put three shots into each zone I then take the bundle home.
Final stage for me is peeling off layer by layer until I find bullets and note approx depth they finished up at - then clean those in water to remove most of paper fiber that gets caught up. Then bag up the samples to be photographed later.
Steve Camp's site -
http://www.hipowersandhandguns.com/ has quite a bit of info on this in various of his test reports.