Just a few minutes south of Denton, on the north side of Lewisville Lake you have:
Lake Dallas Willow Grove - small and fairly open, they say the showers were supposed to be complete by end of May. http://www.lakedallas.com/willowgrovepark_location.html
Hickory Creek Park - nice park with good trees and access to the lake..primitive and electrical sites. Showers. http://www.swf-wc.usace.army.mil/lew...ckoryCreekPark
Sycamore Bend - This is more hidden and less known. But has some nice sites. Not sure if the facilities include showers.
Pilot Knoll - Great place with a lot of options. Has showers...is close to the shops at Highland Village if it gets too hot http://www.highlandvillage.org/Facil...e=detail&RID=1