The instructions that came with my laminate flooring call for a 3/8" expansion gap for floors up to 33' x 26'. My floor is only 20' x 12'. Can I get away with a 1/4" gap? My baseboards are 1/2" thick, and it seems like leaving only 1/8" overlap might lead to a visible gap if things move someday.
Leave the recommended 3/8" clearance gap.
Install your baseboard gently down to the flooring material. If there are minor swails in the floor surface the baseboard may very well leave a vertical gap up off the surface the the flooring material. The way this is normally dealt with is to install base shoe molding. Base shoe is a narrow molding which can easily bend down and follow the floor surface variations.