I don't cover the whole area in glue when I glue baste. I just use a thin stream in a zig zag pattern and it holds fine. When you pin baste or thread baste you don't cover the whole area in pins or thread. Glue basting works on the same principle. I've never had any shifting or puckers doing it this way. I don't like diluting the glue as it makes it soak into the fabric too much. I put the glue on the batting and then smooth the back or top on top of that. This way I don't have glue leaking through the fabric onto the surface I'm laying my quilt on and the batting is less prone to shifting and wrinkles than the fabric.
To make the glue stream more easily you can put the bottle in hot water to make the glue more pliable coming out of the bottle but spreading the glue around once it's out of the bottle really isn't necessary if you use a fine stream. If you get a few globs then pushing them down with your finger works fine but if I hold the bottle high enough off the surface globs are rare.