Welcome to the Drive on Wood site .
I think choosing a truck that will hybrid good ( mixing in a little gasoline when needed ) will be important for pulling heavy loads on busy roads . Short trips or slow speeds will do ok with heavy high profile vehicles but if you try to drive fast the gasifier will over heat . If one builds a gasifier big enough to handle the fast and heavy loads any slow driving may under pull the gasifier enough to make tar .
I think it is best to have a big motor that will have horse power at slow rpms. Also I have found that the vehicles I have used the return-less fuel system work the best at hybrid driving .
The below video shows drawing on the gasifier with the gasoline in the full on position and letting the computer handle the details ( cutting back on the gasoline to obtain the correct fuel air ratio mix .)
There is a huge learning curve with mobile gasification . I would suggest making your first gasifier on a pickup truck and really learn the ropes good before applying it to a livelihood vehicle
Edit . I put over 50 miles on the v-10 today It will eat some wood , about 2 pounds per mile .