Map of public ramps in Texas. You can click for details and pictures of the ramps.
http://txcoasts.comIf you're brave enough for 45 on a weekend:
Louis bait camp is pretty nice. Close to Pierce Marsh and Greens Bay.
Jamaica Beach has lots of fish able water (jumbile cove, gisp, Maggie's cove, etc.) I think running across west bay to greens wouldnt be bad in your boat but watch the weather. The sea isle ramp just down the road is shorter and crappier than Jamaica but it's less idling to the bay if that matters to you.
If you despise 45:
Swan Lake ramp in Surfside. Lots of shell and redfish North of the icw. Go slow and maybe scope it out on a low low winter tide.
Amigo Lane/Ernies - good access to titlum tatlum and the east side of Christmas. Pretty easy to navigate this area. Lots of yakers and can get crowded on weekends.
Points further south:
San bernard river launch to access cedar lakes and cowtrap. Lots of redfish and even more shell. Go very slow.
East matagorda - I've only ever launched from Sargent. East matty is a good big trout Bay. Plenty of redfishy marsh on the back side of the island. Most of the oyster in the bay is deeper than you need to worry about and the shell on the shoreline is easy to spot.
This video helped shave some learning curve off the marsh for me. It's a different animal than the clear grass flats you find more often down south.
http://www.troutsupport.com/dvd-redfish-marsh-grass-flats-shallow/ 
