The biggest thing is insurance, medical personel or ambulance on site, and scoring system. You need to have your track plan approved by insurance with barriers around obstacles and such.
I tried this a few years back with a large overflow lot at the local mall. I actually got approval but the management company sold out to another one that wanted WAY too much for renting the lot.
What I did was I used google earth shots, scaled them and added dimensions, and drew a track layout in black marker on them. Then took a bunch of photo's of any obstacles(light poles, curbs, drain grates, etc), and noted them on the drawing with an arrow the direction I was viewing. "Picture A", arrow towards light pole, for example. This was for asphalt sprint. They may come back and want you to add a wiggle here, or tighten up a turn there, to slow speeds down near a threatening obstacle but they will work with you.
If you are a certain time/distance away from a hospital, an ambulance is likely required to be on site during the races. If it's close enough to the hospital, a certified doctor or nurse may do.
Lastly, most scoring systems are stupid expensive, to the point where it's prohibitive to set up a track unfortunately. I know there are other options feel free to explore them, but this is if you want to accommodate AMB/Mylaps.