I've been trying to figure this thing out for a few years, but just discovered this thread. I have reasonable confidence that I could come up with serious funding for something like this, depending on lots of things of course...
Most of my riding these days is done on private property. One of them is a private flat track/TT course with a few table tops and a few moderate doubles. It's truly a dream come true. It's only about 10 acres. Our trails are spread out over about 50 acres. I'm heading over there here in a few mins to clean up after that big storm! Lots of maintenance...
Noise is our biggest problem. If everyone had stock pipes it would significantly reduce the calls from the neighbors, but I have to imagine that Karen will show up just about anywhere.

Zoning needs to be proper, such as industrial or agricultural. Horse people often hate us, so there's that.
Water is also a thing to be considered, as dust will be a factor in any short track situation.
As for legality and lawsuits, we always point to the backhoe and say " if you get too badly hurt, we'll name our next big jump after you because you'll be part of it!"
Desired infrastructure would be - areas to camp, septic system, a well, a few secure storage containers, maybe an outdoor kitchen area. Byke is going to insist on a stripper pole, so I'll see if Alpinestar still make a G string in his size...
I will check back into this thread