Got ya. Someone else may have a better idea, but that would be my only addition is to consider some type of wingwall/erosion control to prevent future issues. We've built wingwalls for bridge abutments out of large treated lumber for years at work, so you could do something like that fairly inexpensively and tie it in to your structure if you wanted to avoid concrete.
The only other cautionary suggestion I would make is you are likely looking at some significant permitting due to your proximity and flow into the marsh and Clear Lake. Biggest one will be the 404 permit from the Army Corp, mostly because the turnaround time on review for those varies wildly. I put your project into the state PERMT system and it says you won't need state floodplain or sovereign land permits, but that's based on the guesstimated project info I put in. The conservation folks should be able to talk you through all of the permitting, but I am guessing that your location will make it so that the permitting process is more annoying/time consuming than the actual project itself.
