Go to the TL website and look up the rack you are interested in. It should give all of the dimensions. Jot those down, then add the footage as stated by FF to the back and at least one side. Take a look at the pic of the TL to see how far the rear handles extend and keep that into consideration. Mark out the size of the frame on your floor starting at the point that you will place the frame (ie 3' from back wall, 3' from at least one side wall), then step back and see how much room you have at the front of the frame to work. If you will primarily be working from the back of the frame, I would add more than 3' to make it comfortable (also add more if you are a person of larger size).
I just bought a LA and because I didn't want to squeeze it into one of the spare rooms (doable, but not ideal), so I elected to set mine up at our shop about 7 miles from home.