I really like that idea pekkanf and think thats probably the way I will go. as for the up?down hill climb I am going to use a mechanical method so it should be solid enough to cope, soon all will become clear.
Today I started by taking a car cam belt idler and removing the outer bit and remaking it so it fitted into the center of a flywheel this will have the variable mechanism to move the table left and right. Then I made the shaft to drive it and started the housing for this, the picture for this i will post tomorrow.