I agree, get the longer bed. I bought a used Tundra doublecab with 8ft bed although I was not specifically looking for a long bed. I soon realized things would be a lot more uncomfortable had I bought a standard bed. With the 8ft bed, I can fit my tools, spare tires, and airtank in the front, fit the kart in without taking any parts off, and put the folded-up kart stand and fuel supply in the back while being able to close the hatch. I have a hard cover on the bed that keeps things dry and safe and closes almost all the way if it would not be for the kart stand wheel sticking out a couple of inches.
I use the space in the cab for a folding table and chairs, a few boxes of supplies and tools and my cooler and my racing bag.
I can put just about enough in my truck for all I need for a 2-day racing weekend and would not be able to with a standard/smaller bed.