I also have the Hood Lamb. I think it is the greatest view
limiting device I have ever tried.

I also have two Sennheiser ANR headsets which like your Lightspeeds
will not work with the Hood Lamb.

May I suggest a very low tech but pragmatic solution?

What headsets did you have before getting the ANRs? If you are like
me and many others you probably had David Clarks are similar
work alikes. Just reserect on of those and use it for IFR training.
(Older ones are also available cheap because of the great movement
towards ANRs). Like most people, I don't do hood flying for more
than an hour or two at a stretch, so the slightly higher noise
of the passive headsets is not really a problem.

~Paul

We have Lightspeed headsets. ...

I saw a cool product for IFR training which clipped onto
the band of a headset with tiny little bands, and flipped
up and down to limit one's view or move out of the way.
It's called the Hood Lamb

Unfortunately, it only fits on headsets with steel bands,
like DC's or Sigtronics.