My advice is don't do it. It's too risky to take a chance.
We left the Honda 10 on the bracket when we headed up to the PNW a couple of years ago, picked Cal 99 to see some new sights and by the time we got to Sacramento the bracket and transom had cracked. Normally, on a reasonably smooth road, leaving the kicker on may be OK, but then if one meets another strip of road like 99, somethings got to give. 99 hasn't been repaired in 20 years, and it's terrible. The boat got repaired, but now the kicker rides in the back of the truck.
And by the way, that's why I recommend the lightest motor. Hoisting that 110 lbs on and off the bracket and moving it from/to the truck is a bear.
The 150 is OK, since it's bolted securely to the transom. It's not the weight, it's the jostling.
Boris