My pop works for the HCTRA and when I moved back to Houston - from Austin - and needed a place to lay down a lot of miles, dad suggested the shoulder of the toll road.
I'm guessing you mean east of 59 down heading toward the ship channel. I went from Old Humble Road down to East Mt Houston - the road which heads out to Lake Houston. I would do just u-turn and go back, then ride back out there.
I also rode out to the lake a bunch of times, and when there's no one out there, one can ride around the park without fear of being accosted. There are also a bunch of roads around the park which go untraveled during the weekday, so you can navigate around, put in some more miles, then head back out to the toll road and head home.
The wide shoulder was nice and I always found little trinkets along the side of the road. It was a good ride and I miss it since I moved out to the west side of town.