As a contractor, the work levels are safely stored behind the seat of the TV. When ready to level the TT, I use the 4 footer. This may seem excessive, but it makes leveling the TT more accurate and easier. Since the TT is twice as wide as the level is long, all I have to do is lift one end of the level until it reads level. Double that distance and I know exactly how much to lift the low side. No guess work needed.
To be excessive, I also own a 4 foot digital level. The readout can be switched to inches per foot. No lifting one end of the level necessary. Just read the display and double the number to shim the low side. If I didn't already own a digital level, I wouldn't run out and buy one for leveling the TT, but since I have one within arms reach.....