Wet exhaust question

[Tanzerite]

I'm having a very intermittent, but nevertheless critical issue with occasional water entering the cylinder of my diesel and preventing it from turning over. Luckily, no water in the crankcase.
I've had a guy look at the install and on his advice I've ordered a vented loop for the water intake.
However, he feels the waterlock muffler is a little small for the length of exhaust hose. Due to the design of the engine and it's location, changing it is NOT an option (I tried to replace when it developed a small crack and it proved impractical, so I had it plastic welded, so far no leak). He recommended moving the riser loop (probably not the correct name) from just before the transom by the exhaust outlet, to as close to the engine as possible.
Since the waterlock muffler is ABS plastic, I'm thinking I could use black ABS pipe to build a riser right beside the engine right under the companionway step, then drop down and run it right against the underside of the cockpit sole, then switch back to rubber hose to the exhaust outlet.
Does anyone see any problems with this design?
Thanks