Thanks for all the responses guys. The spec sheets desertspeed and derjack linked to have a ton of information, definitely worth taking a look at! The SMB and info from E350 owners about the real-world width is really helpful to. I think this thread will be a good resource for the DIY van crowd, I searched all over the internet looking for information on bed width in e-series vans and couldn't find anything.
@Ozrockrat
I'm about the same size as you (5'9"), and am trying to decide between a bed that runs width wise or length wise. I would prefer a bed that runs the width (more space for storage and living) but am not sure whether a width oriented bed would be comfortable. Sounds like you had an OK experience sleeping width wise in the past? would you do it again? what about for an extended 3-6month road trip with another person?
Thanks for the help guys,
- Tyler