Anyone else do this? There's nowhere on this crappy lake where I could store the boat on-trailer with my mast up due to power lines in close proximity to all boat ramps. Finally I wound up renting a wet slip for $50/mo after long discussions with the marina management about the conversion below. I can pull the 4x4s out in 30 seconds therefore it doesn't constitute "modifying" the dock in any way and doesn't break the rules.
Now I just need to custom cut-n-patch a tarp that'll cover the whole thing nicely and go around the mast and I'll be set.