Strange topic I know 'Roof insulation'

Putting ceiling insulation in the coaster bus and I'm assuming standard house batts will insulate it properly.

I am only ASSUMING this.

I have a minimum thickness in the ceiling of 30mm and a maximam of around 70mm

My questions are...

Are these PINK batts ok to use?
Is there any "caravan" insulation?
If I do you PINK Batts which will insulate better? The 1.5 squashed into the 30mm gap or the 2.5 squased into the same size gap?

The 1.5 is manufactured for walls but is the only difference the thickness and nothing else?

Am grateful for advice...