In that case a socket would be fine, it's just a simple diy device not a high end and fancy one. The socket *can* be soldered, you just have to place the nut and then solder it, but replacing it would become a nightmare in case it breaks ...
I read about washers and nord lock washers seem to be a decent choice (practically impossible to loosen as the pitch of washer is steeper than the thread of the screw, so it needs sufficient force to deform the washer first which will never happen during normal use).
Edit: I can actually buy self locking nuts for cheaper ... Just need to make sure they make good connection while tightening them.