Each reply is worth much so thank you. This past weekend I went on a discovery journey to Kemah/Seabrook and found some great information which reinforced what you have posted.
Josh Johnson a CPYB at Sea Lake Yacht Sales met with me, shared a map (note gave) of Galveston bay and then showed me several places to sail to.
Check out their web site sealakeyachts.com for a link to useful destinations on Galveston bay or his sailboatcorner.com for helpful information.
Watergate marina is a very nice facility with many inexpensive transient slips. To launch I discovered the North end (Seabrook side) of the 146 bridge between Kemah and Seabrook has a nice launch ramp (Texas Parks and Wildlife) and paved pull through parking under the bridge. It is clear of over hanging obstacles so set up of a trailerable sailboat like my Catalina 250 WB is easy and safe. Another ramp and parking facility that is fenced, gated and secure I discovered through Josh, was not in on the weekend so I do not have their particulars yet; Gulf Coast Sailing Center.
Also, he directed me to North Upholstery who make really good looking bimini tops, sail repairs, modifications and such.