We also had last autimn good event with approx 130 km of distance to drive (except going to start and back home from finish - this route took ~ 220 km). From 130 km we had some 55-60 km of gravel. Nothing bad happened, because race track was mesured also with Alfa Romeo and keeping in mind that there will drive Alfas.
The gravel part will be selected keeping in mind, that in meeting will participate only Alfa\'s, that are truely tarmac cars.
There will be approx 1 minute distance between cars, therefore there is very small possibility to brake any windscreens or front light glass by \"flying\" stones.
The average speed on distance also will be limited - because it will be regularity rally, where penalty points are given not only for too slow but also for to fast arriving in checkpoints and finish...
For example average speed for regularity rally last year was 57 km/h. So the speeds are normal.
Different story about speed is racing or cart track. There Everybody is on his own with his car on tarmac.
So nobody from us would like to damage own car. There gravel parts will be specially selected.
Keep on thinking!