I live between lewisville and grapevine - if your looking to launch from the north side of grapevine you do have some nice and easy options.
1) Though I might end up regretting posting this - there is a spot on the north side that is perfect for kayaks right now. I swung by with my wife to look at it yesterday. North Short Trail Head - Murrell Park
- This is normally well away from the lake... but the water is literally 10 feet from the gate right now and there is a small gravel (15-20 car) parking area right by the gate. The road there basically makes it a perfect kayak launching spot - for no charge - and no competition from boats.
2) murrell park is closed but they do let you walk in - and the water is only about 100 feet from the gate. Its a bit of a mess parking right outside as it was never designed for it - but you can and people are. I don't know if the rangers or town are fining anyone for it.
If anyone is interested I'm hoping to get out on grapevine from the north trail head spot for the first time Saturday morning for a few hours. PM me if you want to get together for a bit