The Moab Colorado Fiber Gloss is 245 grams, Alpha Cellulose too and a slightly cooler paper.
Another approach could be a dual sided paper but there are no gloss fiber qualities like that. Ilford Galerie Prestige Smooth Lustre Duo 280gsm is an RC paper also slightly cooler than the Harman. You would reduce the total pages thickness by 60% and the pages stay plane.
Met vriendelijke groet, Ernsthttp://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012, 500+ inkjet media white spectral plots.