Thanks Brian. I had thought of doing something similar, but we are planning a bit of a trip and a few modifications that will require being able to open and close the windows regularly. Also, the lock on one of the windows is broken so I have to sort that out as well.
I think we need to have a good look at the whole vehicle and work out a plan. From the reading I've done so far, it looks like you have to strip a 110 down to a fair degree to do a proper job of sound deadening.

