Sofa Bed with Seat Belts

[B^2]

How hard is it to install a sofa type bed into an e350 cargo van? I found a pretty good deal on a quigly e350 and I'm debating whether to jump on it or not. Most of the time, I won't have passengers in the van but for the occasional trip, I'd like to be able to carry more than just one passenger with a seat belt. The wife and I are looking to have our first kid next year so having something safe I can put a kiddie seat would be great.

 

[rhinojonson]

I never did end up installing a sofa bed. The ones I looked at came with u-bolts that bolted around the frame after you drilled through the floor.