Well your describing a return to battery set up when you talk about free recoil.Small and portable are not prime concerns here, within reason. I am a target shooter so the car is nearby. I dont do prone for the reason you stated. Hell, I dont even do bath tubs anymore because the last time I did my wife had to get in the tub and help me out!!! But I have to admit that at the time I was having a Bi Lateral Pulmonary Embolism, which I survived.
But I want something substantial and with free recoil and maybe even with slides or wheels on the ends of the legs. I think wheels would not work because they would be too slippery. But I dont want the Pod to restrict movement of the rifle as it recoils against my shoulder.