I'm using Kapteyn-b for a story, which orbits its red dwarf star every 49 days. It's almost 5 times larger than Earth, though I've made a couple changes to the observed data to make it more plausible. I've added a CO2 rich atmosphere for a mild greenhouse effect and prevent it from being tidally locked, as well as a Mercury-sized moon to help me fudge the gravity down to 1.4g.
The one thing I don't know is the axial tilt. I'm leaning towards something extreme to give my colonists a real challenge, say between 35 and 50 degrees. With that short a year, what kind of seasonal variation could they expect?
Edit: Kapteyn b makes a complete orbit around its parent star with about 1.2% of the Sun's luminosity about every 48.62 days at a distance of 0.17 AU (compared to Mercury, which orbits at a distance of around 0.39 AU. It has an eccentricity of 0.21, meaning its orbit is mildly elliptical.
2nd Edit: I'm going to go with an 18 hour day length to simplify things.