I feel like a pretty good vehicle for a lot of people like that who need a truck sometimes and don't want a second vehicle could be one of the new small diesel trucks, like the ram ecodiesel. 30mpg is more than even most compact SUVs get, it's still a truck for people that like that, and it can haul/tow more than a compact suv as well.
A big problem with 2 vehicles instead of 1 is often that insurance costs so much more, even if you're driving the same number of miles as when you had 1 vehicle. Registration fees too.
