The easiest simple setup for the track sides are 4 x 4 boards--with a 8" section out of the end-- same on both ends--then the board can "overlap" each other when laid end to end--drill a vertical hole through both boards and pin them together with a large nail. For the turns at the end of a aboard-- use plow disks. Simple, cheap, effective. Look at the 1/5 scale page for LARCRC and you'll find some pics of the track---the inner boards are what I"m proposing.
FWIW
Tim