When me and the wife were still dating I one time to her to Paris (I know, im a hopeless romantic)
At the time I had an open kadett, 4 door but with front seats from a 2 door GSI
They were factory buckets and had the added benefit that they could fold forward into the dash
So when night fell, I just parked on the side of the road folded the seats, pulled a mattress out of the backseat, unrolled it qe were off to bed