Hi, I recently bought a fab Fiat Doblo Cargo small van to use as a second vehicle and camper.  Now with Autumn coming I need to sort the insulation and carpeting.  

I've had a few views on insulation and am not sure what to follow.
1) 12mm insulation as sold by Rainbow Conversions, Cambs
2) Therma Wrap (4mm foil sheeting with a kind of bubblewrap centre to separate two foil sheets) - this claims to give the thermal qualities of 65mm polystyrene, enhanced with carpet on top.
3) Household stuff thats probably too thick for my van

From my pics you will see that there's a lower half with a space between panels (trim removed to show the cavity) and a higher single skin area.  I need to insulate both these spaces, and perhaps do more on the ceiling.

Lower area) There is ample room for thick insulation, with some pushing and shoving I'm sure it would go in! Then I could ply the front of the metal and carpet that - any thoughts??  And how thick should this be - I have some 5mm stuff that was in it when purchased?

Higher area) This again seems rather uneven and therefore tricky, perhaps even a job for a professional. I could put ply right across it but would lose the 5cm recesses (where windows could be on some models), so am uncertain about that - of course this could be a space for thicker insulation, with the foil and carpet stuck on the ply. Thoughts again much appreciated.

Ceiling) I've done the ceiling with the Therma Wrap, finished with the ceiling trim taken from a Doblo car.  This should be quite good protection? There is space between these (between the beams) where I could put further insulation - is that worthwhile?

Floor) There's also the floor to consider - the original 12mm ply is down with a rug on top at the moment.  I dont want to raise this really as I want to keep the space - would ply + carpet be ok (the foil stuff wouldnt work there I guess)?

Many thanks, geoff