The View is diesel powered, so 3.0L is a reasonable size. A 7+ liter diesel in a 11,000 lb GVWR would be ludicrous!
That said, the Sprinter diesel chassis under the View is rated to tow 4200 lbs. As others have said, rolling that much weight on level terrain is manageable, but climbing grades of 3% or more is going to be slow-going. Not impossible, but probably frustratingly slow for some drivers. So a lot depends on your attitude.
For a motorhome, 100 lbs per horsepower is considered adequate and the Sprinter View falls in that range, Towing a 3000 lb toad (14,000 lb combined) would put it at about 75 /bs/hp, which is actually quite decent.