VW camper van roof insulation

[camerart]

Hi,
My niece has a VW campervan, that has a lined roof. 1/8inch plywood, with a 1inch gap, but it feels hot in the sun.

I suggested filling in with expanding foam, but as I will be doing it, am a bit worried about blowing the lining off the roof.
Has anyone done this before and can give me some guidance please?
C

 

[jj4091]

Get the non expanding version

 

[Koolpc]

I would be removing the plywood and insulating behind it. Wall panels should be the same...

 

[camerart]

Hi J and K,
I'll have very little time, so no work involved, just expanding foam. What would be the best way?
I think that as one end it open (by accident) I'll drill holes at the sealed end and let it creep down the van.

Thanks for both suggestions though.
C