Looks cool.

How many miles (or ths of a mile) is it, when you ride the standard route? (I know you mentioned the outer perimeter being 1/4th, but what about the inside?)

I have a makeshift off-road trail in my yard (and partly on someone else's, hehe); It's about 1/2 mile long in full.

On it, you just dodge some russian olive trees, hop over some fallen logs, go up/down some little hills, through sand, over holes in the ground, etc.