I was stopped for speeding (55 in a 40) on a 4 lane divided thoroughfare in Houston, TX. It is in a busy area with stoplights every half mile or so. However I was unfamiliar with the area and honestly did not know the speed limit there (this was the first thing I told the officer), and based on traffic flow and road design I would have guessed it would be higher, e.g. 45 to 50 mph. As I found out later, the closest posted speed limit sign is over 2 miles before the location where the officer clocked me.
My question is: how far away can an officer be from a speed limit sign to stop someone from speeding at the posted limit? Is there a distance from the sign that can be considered too far away? Would that be considered a non-posted speed limit zone, with a city standard limit (e.g. 30 mph)? And if it *is* considered to be an area that is not posted with a speed limit, how can I be legally cited for the posted limit (40 mph) when the non-posted limit is different, even if it's lower?
As you can see from my line of questioning, I'm looking for loopholes to mount some kind of defense. I realize it may be too weak to pursue and I may be better off asking for deferred adjudication, so I'm hoping your opinions can sway me one way or the other. Thanks in advance!

