I wanted to eliminate as much as possible the plastic 'edge' effect, where the cut plastic leaves a white edge to the base. After a hunt around in my bits draw I found some clear plastic from some packaging that I saved.
As you can see in the picture below, the new thinner base is much better (a piece of the previous plastic I was using is shown for comparison).
I now have a basing material I am happy with. I will only be using the clear bases on my 'personality figures' which will be in and around the palace (some 20figs+), the rest will use green bases.
It may be some time before the palace or some of its rooms appear.