First off "Thank you for your service"!
The closest RV park to IAH is http://houstoncentralrvpark.com/
We stayed there when it was a KOA a few years ago. Not bad but nothing to right home about.
The one listed above is "Rayford Crossing RV Park" http://www.rayfordcrossing.com/
Which is located in Spring. Very nice what i would consider highend RV park the last time we look at it.
I would suggest consider a stay at http://www.hcp4.net/Parks/springcreek/index.htm
"Spring Creek Park" is a county park located in The Tomball area. It is a small park with a few RV FHU's that you can call make reservations for one week at a time and its "FREE" no charge. Stay here and do your recon and then decide as to were you would like to stay longer.