I use the same. Clear silicone holds them in place all season I and have them come out about 1 1/2”. You can’t really see them when the boat is in the water unless you look for them. A roll of the tubing cost me about 5 bucks at Home Depot and it will last for many years. I pull them out when the boat comes out of the water so I can back flush and winterize the AC units by pushing Antifreeze in backwards, then put new ones in before splashing again in Spring.