Rather than worrying about a constant radius turn, it's more important to worry about not losing airspeed as you turn downwind due to the perceived increase in groundspeed. This has led to several people losing airspeed/ heading control/uncontrolled gyrations/loss of height/ vortex ring, all sorts of possibilities. Often as a result of orbiting friends house, trying to take photos etc and ending in a big hole in the ground.
Flying a constant radius turn at lowish height on a windy day with the constant variations of angle of bank and ground speed is a serious exercise, but basically involves rolling off the bank as you turn into wind and tightening it as you face downwind which is why it is prone to error.