Pipe Dream. Not as easy as it looks. During a storm and loss of power, it would probably be easier and cheaper to stay at a hotel with power or use a generator (IMHO). And the risk of a BIG problem is great (damage the fuse box, the truck or the grid or all).
The problem with powering from the truck is likely that the neutral and ground are bonded in the truck AS WELL as in the house. Neutral and ground should only be bonded once. His generator (which works with the house) is likely unbonded. The bonding of the neutral and ground in the truck is correct and proper for powering tools in the field but not good for powering the house which is already bonded. There needs to be a way to unbond the neutral and ground in the truck for it to power the house.