This is what I used. PolyGard | Film Pacific
It is made for use on acrylics and polycarbonates. It is VERY effective at keeping out heat. Installation
is challenging, it is very sticky.
I used it on the outside of clear acrylic
- the theory being that the acrylic
won't get hot, so won't expand and contract
, eventually shearing the seals
It seems to work, in as much as the windows certainly don't get anywhere near as hot as the tinted perspex in my hatches does.
Downside is, (apart from the price) it's like a one-way mirror. At night, if it's darker outside than inside, you can't see out.
Looks sexy too IMO.