We had a u shape van furniture kit , but had our cushions made by a caravan/ motorhome upholstery company as I changed the layout to a L shape, this enabled us to go for a slightly firmer 75mm thick foam, instead of the VF 100 mm, giving us a little more headroom when the roof is down. we could then also use our choice of fabrics.
We use our 50mm Duvalay mattress topper on top of the cushions anyway, when sleeping downstairs, super comfy.
I think they were about £600 for the 4 cushions, we had a piping round the edges in a different colour.