No one is going to stop you-- unless you speed-(a lot over the flow of traffic), cut in and out of traffic, and if you roll the coal-- look out! :gearjamin
In general, there are very few highway patrol running the freeways, and the ones there, are looking for the easy catches, or writing up accidents.
If you tow a trailer in California-- the max. speed is 55 MPH. You can fudge a little if you stay in the right lane and go with the flow.