LOL. Wow, seriously? Can you please tell me why a radar will confuse a towed decoy for an F-35 if it has an extraordinarily high RCS? The goal is for the towed decoy to mimic the F-35 in every single way possible, that's the point of a decoy.
When hunters go out for duck hunting, they go out with a duck whistle, not a bugle.
The decoy needs to be around the RCS of the aircraft, or even smaller. If it is far too reflective, you can teach the missile to reject it as clutter so it can target the actual aircraft.
You are confused about the reason why the decoy exists. If you want a highly radar reflective decoy then you can't have it chasing you around. What you need is something that saturates the air with RF so radars and missiles can focus on it while being as or less reflective than the aircraft carrying it, not more.
It's not a big secret why the F-35's towed decoy doesn't have pictures on the internet.
It can be powered by both the aircraft and the battery. When powered by the aircraft, it can perform EA to its full design.
But when discarded, it can retain the signals it needs to emit within a memory bank for the few short seconds it needs to transmit, and a battery to power those few short seconds until it can do its job. So you've got a missile after you, then all you have to do is release the decoy and move away. The decoy would glide for the 10-20 seconds it takes for the missile to reach it, and you are long gone by then.