Probably a little late to chime in here, as lots of arguably better advice has already been given. I flat towed my FJ40 from Oregon to southern Utah (1100+ miles) behind a Jeep Grand Cherokee, 2003ish, V8. For the most part it worked out fine. A few lengths of highway that were particularly rutted caused some tension, but no incidents. Depending on the alignment of the 40 slow speed maneuvering can be a nightmare. It was with mine. Every time you went around a corner the wheels would turn full lock and refuse to straighten out. Maybe it was because I didn't have a steering box installed so there was very little drag in the system. Regardless, the solution we came up with was to use some very big zip ties (the 2ft x .38" variety) and double or triple them up between the frame and the steering linkage so the wheels could only turn about 30 degrees either way. This way they still always wanted to center and they still had enough movement to not scrub on every corner. I probably should have taken a picture, but basically we ran zip ties through a hole in the frame behind the bumper and around the rod ends of the track rod, leaving them loose enough for the wheels to turn a little, but not too much.
