The tell tale oulet is modified by us for the RNLI Mariner 40s, ( hope i dont get told off for tell people this!!)
We take the tell tale fitting off, drill the hole out to i think its 10mm and push the hose through the hole. Then put a cable tie on the outside of the cowl tray to stop the hose going inside the cowling.
We have done it to stop it getting blocked up. It wont effect your engine.
The RNLI have been using this system for a long time with no problems.
I spent hours measuring temperatures and water pressures on these engines and gradually made the tell tale hole bigger and bigger to make sure the would be no effect on the engine.