I am a big fan of inflatable type boats, particularly Zodiacs. The military uses them a lot for stealth activities because an engine silencer can be installed to make them almost unheard when running full out above the noise of the surf. When idling the engine is barely heard at all. The same type technology is used on the stealth type mufflers used on hunting quads. My son broke the exhaust on my quad, but the Hush Power I now have to reweld/rebuild made my quad’s engine run almost silently. It was barely audible when going at slow speeds and you heard the crunch of the tires at high speeds long before you heard the engine.
When being stealthy in a boat your profile is what will give you away long before anything else… According to what we were taught in the Navy. There are black or dark blobs all over waterways to include rivers and lakes. Shadows can cause similar looking blobs naturally as long as you don’t sit upright. Why do you think that the Navy has silhouette pictures of ships for identification and not colorings? There are always all sorts of pictures of their radio towers, radar dishes, etc…..
Other things about inflatables: They are easily deflated and reinflated for purposes of hiding them while on shore. Hard hulled boats are a bit more difficult to hide onshore.