I'm designing a hypothetical lower-gravity planet with 0.47M, 0.79r and 0.76g, with a similar density to Earth. I've already determined that this mass, radius, and density will allow my planet to sustain a long-lived internal dynamo and strong magnetic field, as well as have an escape velocity that will permit the stability of water vapor in the atmosphere. I want to give the planet an Earth-like atmosphere (in terms of composition), but the fact that the gravity is lower might mean that the atmosphere would be less dense and expand farther out. I'm worried this might make the planet too cold, and I don't want a snowball planet scenario.
My question is - if I want the planet to be at least as warm as Earth was during the last ice age, what factors should I tweak to make the planet realistically warm enough? (I'm thinking maybe increasing the total mass of the atmosphere, ocean size/depth, rotation rate, etc). I have some general ideas but no confidence that they make sense. Does anybody with a background in astronomy know?