Galverston to Sabine Pass Port Authority is around 70 nm (fuel available)
Texas' Safe Harbor Marina | Sabine Pass Port Authority
From there to an anchorage in Lake Charles is only around 37 miles but the next possible stop is Lake Arthur anchorage (no fuel) which is an additional 52 miles.
Lake Arthur to Fresh water bayou (Fuel available) is 35 miles or you can continue to Morgan city which is an additional 35 miles. From there to Houma Municipal dock (no fuel although there is a fuel dock about a nile away) is 67 miles.
From Houma to the East side of the Mississppi is 69 miles. Seabrook marina is an easy fuel stop. Your next fuel would be Gulfport or any of the many area marinas.
Do not get in a hurry and get stuck in the middle of nowhere as there is simply nowhere to 'pull over' and there are bridges and locks which can really slow you down. Many have curfews and will not open when schools buses are running or during rush hours. The Southern Crusing guide is your bible. An AIS is extremely helpful.
Let me know if you have any questions.