A very late follow-up to this thread. My wife and I finally found the van we wanted:
2009 E350 SuperDuty Diesel, EB with a Quadvan 4x4 conversion. We bought the van with under 15k miles for a very nice price. The van has some nice upgrades: a lift, upgraded wheels/tires, tinted windows, wheel flares, etc.
I've read extensively on the 6.0 problems and while they clearly exist, it is also clear that the 6.0 problems we primarily with the earlier engines; later engines seem far more reliable. There are some reasonably priced bolt ons (like EGR cooler and coolant filters) that are worth while additions.
As this is an E350 SD Diesel, I believe the rear axle is already a full floater, but I am not certain.
We are off to Quadvan in July to have the PH pop-top added. We live near Van Specialties and will likely have them do our interior.
All in all, we are extremely pleased and very excited about getting the top done!
Our blank canvas: