I think Weston Lakes would be your best bet for the property size. You could get an extremely nice house for that amount, or even much less. I don't know much about Lamar ISD, but like lots of things, I'm sure its growing and improving. You might be willing to commute the kids to private if you get a great deal on a house.
An associate of mine lives in Weston and loves it. However he and his wife are almost 70, so that really slow pace appeals to them.
I know some places in Katy like Grayson Lakes,Lake Pointe, Lakeforest have bigger lots, but I also think foreclosure is a big issue in those areas. If you can catch something in Windsor Park Estates, I think coming from NC you would be very happy with it and its solidly in KISD. Here's two listings there.
19018 Oak View Terrace, Houston, TX 77094
1618 Cambridge Oaks Cir, Houston, TX 77094
Unfortunately it is hard to find homes in the xburbs, in true a community, with an acre of land. I don't know if its because most people don't want to be bothered by that much work or the more likely factor of developer greed.
City of Houston has areas with an acre, but that's over a million.
Ps- What is your definition of isolated? If I have to drive more than 1 mile to a grocery, and more than three blocks to minor needs locations, I consider that isolated. So to me Weston Lakes is very remote, but to you it might be just right. You really need to take a week and drive the areas.