Like this do that. You guys in the southern hemisphere appear to have more sense when it comes to stuff like this. AA62 has a wealth of experience and would have welcomed such a bit of kit in his day. I never felt particularly safe in one of our belts. Our RW boys ditched it a while back. The guys at Irvin based in Letchworth UK had proposed a similar device to yours some time ago but it was never taken up. The belt was considered safe enough to declare ALARP.
Does anyone know if we [UK] have these Datum Marker Buoys on inventory. I noted from the other thread they were still talking about pyrotechnic smoke floats in relation to ASRA. Would be so easy to take one of PSI (QNA) PADS Dropsondes waterproof it and frig the software so it did not stop transmitting when it stopped falling.