Well, I can assure you that motorized bicycles aren't against the law here in Texas. We do however have a lower legal engine size than the other states. Of course, your 66cc engine isn't legal in the the state you live in now.

Here's the
actual law. As you can see, we have a maximum engine size of 38cc, instead of the 49cc that all other states seem to have.
Anyway, if you're going to have a 7.5 mile commute, that can be done on most electric bikes, as long as you don't have an aversion to pedaling. If you're going to have a 30 mile roundtrip, though, you can forget about electric. No matter how much money you have to spend, a 30 mile commute at top speed is not going to be happening, unless you have an inordinate amount of lithium batteries. The expensive ones that can do 30-40 miles can do 30-40 miles @ 10-12 MPH, not at 30 MPH. BTW, haven't you noticed how many people on motorbicycling.com are from Texas? They all ride 66cc bikes.
Talk to GeorgeNTexas, longhorn6, and the guy from Granbury who goes by something like "fall_down_stand_up". Those three all ride 66cc two-smokes, and besides the fact that they break down every few miles

, they don't have any complaints. The cops in Texas don't have anything against any type of bicycle that I have ever seen or heard about, as long as the rider is riding responsibly. Most of them actually think the ones with dinosaur burning engines are cool (this is
the oil state, after all).
As far as the streets of downtown Houston being dangerous for cyclists, I'm sure you're right. They're quite dangerous when you're driving a 5 ton SUV. I know for sure that at least 90% of the licensed drivers in Texas should be walking anywhere they go, instead of driving vehicles that outweigh M1A1 tanks. I still think you're just worrying about something that you shouldn't be. If you have any problems, just do what I do: shoot first, ask questions later. The cops won't bother you about that either, since it's what they do themselves!
edit: BTW, everything you've heard about Houston traffic is true. The first time I drove to Houston, I got into a stop and go traffic jam-- at 10:30 PM on a Sunday night. The last time I was there, it took me 3½ hours to drive from one side of town to the other. That was during the middle of rush hour, though.