Not to tow, although the Focus just might barely fit into the 13,000 pound GCWR of the E-350 cutaway with 5.4 V-8.
I have both E-450 with 6.8 (very heavy motorhome), E-350 with 5.4 (but slightly taller gearing than the cutaway, 12 passenger van). The V-8 is frequently on the edge of unlocking the torque converter or even dropping out of overdrive at highway speeds when I'm moderately loaded and not towing. I suspect towing with the E-350 carrying a motorhome that large is going to mean locking out overdrive, moving cruise RPM from something in the low 2000s up to something over 3000 RPM. The engine can do that, but it is not fun to listen to.
