Des Moines area here. We head straight south to Carthage, MO also, where we dewinterize at Coachlight RV Park. If its still too cold there we sometimes head on down to Oklahoma City to Twin Fountains RV Park where we dewinterize.
Once at Oklahoma City we follow I-35 down to San Antonio then take 281 to McAllen. Now you're in the Rio Grande Valley and have 300-400 RV parks to choose from all the way from Palmview west of McAllen or east down to Brownsville and South Padre Island.
Other times we will cut down from Carthage to Sherman, TX (Lazy "L" Rv Park) and then head over to I-35 and the west side of Fort Worth and then on down to the Valley.
Just some ideas on fishing:
http://www.themonitor.com/article_99b617ec-d471-5168-93bd-7315f919d087.html
Good luck!
