I have much the same issue with a piece of the lake backing up onto my property. Look at the houston craigslist and type in "flat shipping rack". I found this guy who sells these things, he goes by Forklift Mike. They are 40ft long, weigh 11k lbs and can handle a load upwards of 100k lbs. I plan on building a couple piers on both sides of the lake and then setting this across. I think the weight will keep it in place during the worst of floods but I'll chain it to a tree or something just in case. If you don't have the equipment, you'll probably need an excavator or crane for an hr or so to set it in place. Just a thought. Mike said he sells alot of these for bridges. He sold two last in the last couple of weeks to guys in Madisonville for bridges. My place is in limestone county so I'm paying Mike to bring it up there. I only have a 27' flatbed.