Really nice layout, which I really like.
However, few things...
...if I was to use this on my server, a lot of drivers would just ignore the chicane near the end (before the hairpin), by crossing the checkpoint and immediately swerve right ignoring totally the first turn by heading for the second. They would also shortcut some other corners.
This is especially true where you use an InSim to record lap times. Most drivers will follow your route, but some will just want to show on top of score sheet, and so will try find where they can cut corners.
On open layouts like this, best to use invisible marshalls to stop drivers cutting corners too much, and to use route markers to make sure they actually follow the route you meant (see attached example).
Also, if using checkpoints on open layout, why make them so big? This allows drivers to take routes outwith track and still hit checkpoint. Use the W and E keys to make them just wide enough to cover width of track.
If running out of objects, where you have a long wall of long barriers, try swapping some of them for the longer armco barriers. You could try barrier - armco - barrier - armco - barrier, etc. If you used them at the spawn point leading to the your start, you could save about 4 objects (some of which [speed humps] I've used at the first chicane corner [in first image]).
Hope you didn't mind the comments I made!