I would be very interested in getting more details about the
problem you are having with the Newest Nodes client, so that I
(or Shendal, but most likely the problem is in my end)
can fix it. I have tried to make the NewestNodes.pm module
resistent against some of the server "misbehaviors" that I have
encountered, but I'm sure I haven't encountered all of them.
Once you get the Newest Nodes client working, it should serve
your original purpose, because it marks read nodes in a different
color. And the latest version even keeps persistent state, so
you can exit the client, come back later and still know which
nodes you have read.