I mainly do short ovals and have tried multiple ways to create the track surface. Splines for the track surface just never seemed to work for me. Bend modifier was even more painful. In the end, Im sorta using the ISI tut way, creating road, walls, fence, texturing, etc. in about 50 m sections. Then I will add 2 or 3 sections together and use the ffd 4x4x4 to bank and bend. With the current way I do my dirt ovals, I will loft the walls and fences after I create the track surface. Granted I tend not to stray from anything over 400m long, it works for me.