If you're doing the Ditch, go through Lake Borgne to the canal, rather than through Lake Pontchartrain (unless you want to go there). You'll have a set of locks to traverse to get to the Mississippi (which can take quite some time if there is heavy barge traffic).
I was going east, so used the Harvey Lock on the west side of the River, so I'm unfamiliar with the downstream lock. If you go up to the Harvey Lock though, be aware there is a bridge that doesn't open during rush hour (4-6pm, I believe). Can't say if you'll make the west side of the river on day one, but I wouldn't plan on it, too many variables you can't control.
My plan would be to head for the marina just north of the canal (or up to Lake Pontchartrain for one), then cross the river on day two through the Harvey Lock, then stopping at Boontown Marina (I don't recall any good place to anchor, but that doesn't mean there aren't any. That will get you to Houma on day 3 and then Morgan City on day 4. Day 5 will either be trying to find a place to anchor, or, if you have crew, following a barge through the night (what I did). You'll have 1 set of locks to go through, which I did at night.
If you anchored on day 5, day 6 will get you at least to the Mermetau River which is a nice anchorage just off the Ditch. Between there and the Calcaseiu River you've got a couple of pontoon bridges and a set of locks. If you're needing fuel, you'll have to head up the Calcaseiu to Lake Charles (4 hrs).
Now you have a choice. Head down the Calcaseiu to the Gulf and go offshore to Galveston or further south, or stay on the ditch. I'd choose outside.
If you stay on the ditch though, you have a bridge (50ft clearance) just west of the Calcaseiu that requires a 4 hr notice to open. And, if you don't get through it early in the day, you're going to run out of daylight with no place to anchor. (On the east side of the bridge is a barge switching point, lots of activity) Ideally, you'd want to start your day just east of the bridge and then either anchor at Star Island, or go on into Beaumont/Port Arthur and find a marina. From there to Galveston, there are no good anchorages except just south of Port Arthur. Again, you could go out the Sabine R and offshore. (I would stop at Star Island, then just south of Port Arthur, and you can make the Stingray Marina the next day, or possibly even Galveston.
I haven't been south of Galveston, so can offer no help for that part.
when you get to galvaston there is a small place called offets bayou if you go up the channel about a half a mile and go south there is a good dock and you can stay there at no charge and the store's are very close ! like 1/8th mile! the fuel is cheaper there and you are out of the way of everything! good spot to rest!