Indeed, the game actually generates each 32 pixel block (enough to hold a single object) as needed using an RNG. I don't think the game would crash if you let it continue indefinitely using cheats, but the absolute hard maximum number of sections one could reach is 2000, since each bridge is worth 500 points and that would get you to 1 million with just the bridges. Of course, some levels have narrow parts where you need to score some extra points, so it'd be more like 1900-something.
I sent my map via the "submit" feature on the site, but didn't get any feedback. I assume there's one or more mods who will determine whether to add the map to the site or let me know if I should change it somehow?