Is it possible to use Kerdi fix to effectively glue kerdi membrane to a fiberglass shower base? I have kerdi on cement board coming flush with my shower base flange. My original thinking was that I would use Kerdi band to join to the base, however, I am thinking now that Kerdi-Fix might not dry between two impervious layers (the fiberglass flange and the kerdi membrane). My other option is just to seal the crack with kerd-fix, but this seems a little weak.
I would install the cement board over the shower base flange about 3/8-1/2" away from the bottom. The walls would be shimmed out to be in the same plane as the flange so the cement board doesn't kick out at the bottom.
Having an open seam at the bottom doesn't make sense as it will constantly be exposed to water.