Just how bad is salt water for the engines? Cut a hole in the landing barge and hit that, with struts mounted 2/3 of the way up to catch on the sides of the hole.
Actually -- make the hole a steel cavity projecting below the waterline, with smooth sloped sides. Thus a miss hits the cavity side and the rocket slides down. Put thrusters at the top of the rocket to push against the pitch torque when the thing contacts the cavity. Drop your struts from the top of the rocket on to the barge.
Now you've got a lower center of mass and wider "legs". You will for sure bang up the side of the rocket, but so what, it is the engines that you really want to recover. (Hmm, actually it will be the rocket exhaust that hits the well first anyway, does pressure in the well from the rocket exhaust help at all? Might slow down the descent, might increase the pitch torque.)
Actually -- make the hole a steel cavity projecting below the waterline, with smooth sloped sides. Thus a miss hits the cavity side and the rocket slides down. Put thrusters at the top of the rocket to push against the pitch torque when the thing contacts the cavity. Drop your struts from the top of the rocket on to the barge.
Now you've got a lower center of mass and wider "legs". You will for sure bang up the side of the rocket, but so what, it is the engines that you really want to recover. (Hmm, actually it will be the rocket exhaust that hits the well first anyway, does pressure in the well from the rocket exhaust help at all? Might slow down the descent, might increase the pitch torque.)