We wrestled with many of the same towing questions when we were looking some years ago.
At the time, for a class B, the options were Chevrolet 6.0 power, Ford V10 power, Sprinter 2500 (single wheel rear), or some version of Dodge if it were used. All the "new" units at the time were either Chevrolet, Ford or Sprinter based.
We quickly ruled out Sprinters as the tongue weight would have put the rear axle over it's limits - so no way. (The newer dual wheel Sprinter "might" have won at the time, but there were none yet.)
So, that left Ford and Chevrolet as we didn't want "used".
One of the key measurements was the distance between the centerline of the rear axle and the centerline of the ball on the ball mount. The Fords had a shorter wheelbase, so a longer C/L to C/L measurement. The Chevrolet was 15 inches shorter C/L to C/L.
The shorter the C/L to C/L measurement, the less sway and better control one has over the towed unit. Also, the shorter the measurement, the less weight is put on the rear axle (since more is transferred forward).
Flat and level towing - OK, it's not a big deal. But, in the mountains, twisty roads, downhill, etc. - it's a bigger deal.
Along the way, I asked my wife to sit in the passenger's seat of both a Ford and a Chevrolet. I asked her to sit there for one hour. Take a book with you if you like, but sit there for one hour.
The passenger footwell in the Ford is VERY small and confining. The Chevrolet footwell is MUCH more comfortable for the passenger. The driver's footwell is comparable in both.
My wife didn't make it an hour in the Ford, got out and said "no way".
So, the numbers for the Chevrolet made better sense, and she was comfortable, so now it was just finding the upfitter, floor plan, and options we wanted.
We looked and looked and looked and - well you get the idea. But we kept looking.
Quite on a whim, we stopped at a dealer about 100 miles from us, took a look, and it was right - down to the details. It took about three minutes to make the deal, we left, went back a week later with our checkbook and we still have the unit. No regrets. The work we did upfront has borne smiles year after year.
FWIW, the factory hitch is 10,000 lb. But the "rated" (owing to the weights added by the upfitter) towing capacity is only 5,000 lbs, so as to stay within the Chevrolet GCWR.
We also added a proportional brake controller for the trailer brakes, a thermostatically controlled ATF cooler with dual fans, independent air bags on the rear axle, and a few other smaller items.
We have a 2008 PW Lexor with 6.0 power and a 4 speed transmission.
My wife and I are a couple of happy clams (or is that campers) with it.