Noah et al~
Lots already covered here. I always anchor - not stake - an untended vessel. If you are concerned that a rising tide might strand your "transport boat" up on the marsh, 2 anchors - bow and stern - do the trick.
Having said that - here is the "staub" or "bog spike" or "marsh...
All~
I just completed the restoration and customizing - my "spa treatment" - for another South Bay Duckboat:
One of the features I have added is an "underdeck storage tray" - which I have made for other South Bays where the owner placed the gas tank up forward, beneath the foredeck. This...
Craig~
Nice project! I have not seen these particular Herter's models before. They are Herter's Model 72 Mallard/Black Duck bodies - but with no molded keel and a cavity to receive a vibrating "puck" to make ripples.
I have also not used Trex for keels - but it makes perfect sense...