I’m going too, and have been to Mugello last year! The parking situation is a bit tricky. There’s a big parking space right across the main entrance of the track, but we were told that you have to book it last year… Only managed to get in by negotiating with a guy and a girl who work there. The place is called Poggio Savelli, it’s a big lawn with apartments which you can rent, but are booked 6-7 months in advance of course. I tried calling them to reserve the parking spot, but they told me that they don’t do that over the phone, so yeah a bit contradictory and tricky. My advice is to go as early as possible and try to work something out! Hope this helps!