if the seat post has a removable collar , you can get a whole different collar.

Otherwise, I'd suggest just getting a long enough bolt and a nut...
the fact that you will need a wrench on both ends, because the bolt will just rotate
if all you have to Nick a saddle is one, is the security improvement I.s think..

Yea, there are Pinhead and other replacements for the skewer of a seat post QR

Hit up the Bike shop and see what they can get.

people have used their old bike chains and covering innertubes, to go between the seat rail
And a frame tube , It will do it too.