1992 Airstream B190, 8 cylinder 7.5 Engine, 41300miles, regularly serviced and professionally winterized. was asking $16000 NOW $12000 OBO!!. Currently stored in Lincroft NJ, 1 hour south of New York City.
We are parting with him only because B190 does not accommodate a car seat safely for our baby ...

Thanks, craigmar!
Yes we have lap belts, but our concern is actually the sofa being too soft and side facing.
This is a website that I have discovered so far, and it seems unsafe to mount a car seat on side facing seats.
http://www.car-seat.org/showthread.php?t=14960
However they say ...

my partner and I came back home with a little one in my tummy after 5 months of traveling across the country with our 1992 B190.
Now our daughter is 4 month old but *Oops* we did not think about the car seat!
Is there any way to securely, legally put an infant car seat in B190?
We absolutely LOVE ...