I thought I might make some stuff that could be easily mounted to a 6" x 1" x 6' plank base...
Here goes, a dual lane, retainer pins starter unit, [3 and an extra screws included],  wood screws go through the starter and into the TOP of the plank,  screw goes into the END of the plank..
Note the END hole to the right of center, the horizontal 5/16"- 18 bolt lets you screw on another nut till that end is heavy enough to retain the cars [no elastics or springs] ;
Brass handle, a 3/8" stroke starts the cars, pins are 2" apart, the cardboard box is to resemble the plank's position ;
top 2 mounting screws are about 5" apart