I realize this is an old thread, but I just happened upon it because I am also looking for guidance on getting a clearer "clear" material print.
I have found a "tune" setting on the Ultimaker3 printer that I think addresses this issue. Under the "Tune -> Extruder" settings is a "Material Flow" setting that can be adjusted from the default 100%. I haven't tested it yet, but it seems that it would accomplish the multiplier effect that you were looking for.