Houston Marathon Spectating Question

Hello r/Houston, looking for anyone who has some experience who can help.

My wife is running her first marathon in Houston next week, and I'm going to be trying to pop up at multiple points along the race. I'm using a bike to get from point to point. Does anyone know if there are points where I'll be able to cross the course, or is the entire route complely blocked off for the duration of the race?

Trying to figure out if I need to get there early to pre-stage myself in the area in the middle of the course, or if I can start at the start, cross in the middle, and then be there at the end.

Thanks for any help!