Boats? A lot will depend upon which scenario is faced.
Tech down? It may well be as simple as waiting until a foggy night, ala “To Have and Have Not” to get where one wants.
It also may depend on just how good a muffler is used, and what speed?
I have watched Fish and Game guys idle up onto people fishing on the banks of rivers before, unnoticed until the last second in broad daylight, the border patrol does the same.
Japanese patrol boats during WWII were routinely avoided by the coastwatchers in the Solomans, even when carrying downed aviators.
I’ve sat on lakes and watched small boats (10hp motor) putt along without hearing anything.
One of the best poachers I ever met had a midsize jon boat that he used to transport deer, as well as running a small trawl net. The boat was coated inside with bedliner to cut noise, but the key was the muffler system. 100′ away you wouldnt hear a sound unless he opened the throttle up.
He actually ran right under two wardens on a bridge, they were too busy chatting about the previous evening to notice.
A boat opens up possibilities that aren’t available on dry land, plus the possible escape routes.
Saw a truck just a couple of weeks ago with a sea kayak, here of all places. It was heavily camoflaged and had an electric trolling motor mount on it. He was getting a multicolored skirt/cover repaired. I sincerely doubt its used for duck hunting.