Sportfish market in the 50ft range; 1980's through 1990's.

Love that pic, Silverado is 120' !

I have seen yachts up to 63' hauled by trucks, the beam was 17' - 4". CA to FL. It all comes down to what is the bridge / break down point? There is a point somewhere in Georgia where they get off the beaten path and they always delivered with a scattering of Pecan's in the bridge /cockpit. Carver's Voyagers are trucked over land, but they typically use two trucks as the entire Bridge is a second assembly.

Reach out to the boat trucking companies like Justus and others, they have the straight scoop.

First, it's CUMMINS = QSB engines pre 2005 are 24 valve; earlier models pre-1998 are 12 valve mechanicals, inline six cylinders - easy to find parts - even easier to work on. QSM's are newer up to 715hp, but really who needs that much - you'll be pumping 30-65 gph.
Second, Detroits are notorious oil burners. I should know, I have four on my tug - and parts are hard to find at times. But I love mine and they've served me well over the past 25 yrs.
Third, Cats are expensive to work on and less desirable than the previous two.

If you want to bounce around the ocean - pick a Hatteras or Viking. If you want a smooth ride pick a Bertram, Post or Cabo - with low freeboard.

In my previous life, I hauled boats, horses and rv's. With flaggers and permits, I've pulled up to 85ft - WA to SC and back more than a few times.

In the past, I have used Dudley Boat Transportation out of Washington quite a bit, he would deliver to places where others couldn't and his ability to navigate mountains in snow with an over-sized load where unbelievable. Never met anyone with his transportation skills, an ex- Indy racer at that.

On your 85ft long loads, where those one or two vessels on your rig?

One, and the bridge was assembled later. I have hauled up to three on a low-boy