I have a 2017 MBS 2400WS and the only time I am unable to see a vehicle behind the trailer I am pulling is if they are so close that they don't belong there in the first place. Here in Michigan we run across quite a few econoboxes who will try and draft you to save on even more fuel. The solution, SLOW DOWN, they will pass.
The main drivers mirror is fine for seeing anything more than three car lengths back, if adjusted properly. The convex mirrors below it will pretty much cover anything alongside you.
The main passenger mirror is another story all together though, but only due to the roll up canopy arm. I suppose if you wanted to live without a canopy, you could get a better view from it.. the solution to the lack of view on the passanger side, stay in the right lane unless passing.
What really amazes me is how so many say FR should do this, or MB should do that... How much extra are YOU willing to pay for THIS or THAT. If you want motorized extendable mirrors like the ones that are available AS AN OPTION on pickup trucks, go to a truck accessory store and have them installed.