VW T5 - Van insulation - What to use?

I considered all the options, read dozens of blogs and forums and I've decided to go with the following:

A layer of foil bubble wrap.
A thick layer polyester insulation
Everything sealed in with foil radiator backing.

There doesn't seem to be a definitive solution, many professional van converters seem to use a layer of foil and then rockwool for the bulk of the insulation. I wanted to avoid this because it contains glass fibre and is therefore unpleasant to work with, not great to sleep with and it also absorbs water. I suspect they use it because its cheap, affective and they don't have to sleep with it.

The three other methods are wool (expensive), kingspan (expensive and you can't push it into the corners) and expanding foam (very expensive and a nightmare if you need to access the panels)

The materials I've chosen are easy to work with and relatively inexpensive. The disadvantage is that the polyester will potentially absorb water, but I intend to seal it in and if it does get damp it drys fast (unlike wool).