[duke36]

Suggest not insulating with fibreglass or other synthetic materials. These products can entrap moisture and foam can disintegrate over time especially with a black vinyl heat absorbing roof. It's suggested to allow the roof materials to breathe as much as possible so as to not allow condensation buildup under or above (depending on climate and temperature conditions) the foil membrane.
An alternate system which some prefer is to remove the chicken wire and install 1/8" 'masonite' type board overlayed by indoor/outdoor carpet and then the vinyl roof covering. This gives a stable roof and a little more insulating capacity when used with a cotton or other natural fiber based breathable headliner. The contact adhesives can act as membranes eliminating the condensation collection issue. The downside can be replacing the vinyl as it's glued to the carpet substrate.