It appears that it's legal for a bicycle to use an interstate in Texas.
http://www.txdot.gov/inside-txdot/mo...cycle/faq.html
I would avoid Friday's after work because there may be more drunks on the road.
If there are no street lights on the interstate, you will need some very good front lights to see the road/shoulder.
You should check out the shoulder ahead of time in daylight. You want to locate hazards that might not be visible at night. You may also want to locate what the area to the right of the shoulder is like, so you are prepared to avoid the bad apples. The local police might be able to give you some information regarding these bad apples.