hi i fit bus and car glass all day ,standard automotive glass is 5mm ,you could have glass made up in smoke colour.if you fit perpex its not very strong. and cracks very easy .wot you need is polycarb but it is not cheap its fitted to police vans ect and near unbreackable ,there is also lamanated glass same as windscreen,you can buy smoked, i used to do a landrover ambulance last year.hope this helps