To be frank, I don't think they'll be looking for you. A Radar isn't a magic torch which will see anything and everything. Furthermore, the radar isn't used for detection of other aircraft at low level (as far as I know...AD notwithstanding!). The radar is used for TFR (a scanning monopulse), fixing the kit and terrain avoidance (GMR). Whilst there might be some radar reflection from your rotors or pod, it is likely that the bright up they produce will be lost in the ground return or gained-out at high gain settings.
The big sky principle works. If all else fails, see and avoid.
Blunty