How to increase / remove the map size limit when editing a track in Trackmania Nations Forever

TrackMania Nations Forever is a free version of Trackmania. I originally purchased the United Forever title in which you would receive more environments. The games themselves are Identical.

Trackmania 2 Stadium features all that you mentioned over its predecessor as well as an improved track editor and improved leader boards.

Essentially $5 (December Steam Sale 2013) gets you an upgraded Environment and editor with their version of a workshop where users my buy/sell/trade tracks, car designs (and more?).

As far as I know, there's no way to prevent players doing this.

You should consider why it's a bad thing to have the player be able to go backwards here, given that unless the player is incredibly skilled (ie. likely to win anyway) they're not going to be able to consistently land this method, and that it's quite slow to execute.

If your intention is to prevent players using it to take a shortcut, then you may want to consider additional checkpointing to close that loophole instead. Alternatively, you could use a jump or ramp to prevent travel in the reverse direction.