Does anyone have any experience or expertise on designing a cathode protection system for steel structure?

I’m in the process of building a boat house with steel pipe driven into lake bed and want to design some anti corrosion system

we have cathodic protection on several of our underground storage tanks. I work with our on installation electricians when I do anything with them. Our electricians are the ones tasked with monitoring the condition on them. Over time there is a part that slowly degrades on them - like a sacrificial anode or something.

You need sacrificial zincs, You probably won't have as much problems in fresh water but any dissimilar metals in salt water will degrade fast.
Make sure any electric lines are well grounded in the vicinity and check the zincs every 6 months and replace if degraded.

Knew a guy that welded Zinc wheel weights to the steel post's on his dock, never heard if it worked out or not.

Yep, sacrificial anodes and constant electricity. It doesn't require a ton of voltage, but you need to keep a close eye on it and change the anodes when needed. We do this for Ductile Iron Pipe waterline installation in close proximity to steel gas lines or other utilities