Nah, if your Tundra works for you why bother? Especially if you have it paid off or a good part of it.
I've seen a couple of Tacomas with similar racks, including that rack system from Thule or Yakima that slides around on the bed rails. I've seen some older Toyota trucks with ladder racks and the works. If it has enough payload for the type of work there isnt much of a reason to purchase a larger truck, especially with the high gas prices, maintenance costs, etc.