I think that the interior layout of my '95 C320 is similar to your C36. Last time I replaced my 4Ds I put a 2X6 across cabin, resting on the shelves above the settee. I used a 4-part block and tackle slung from the 2X6 to lift each battery from beneath the berth onto the seat of the settee. I slid each battery back along the seat, and then did the only "dead lift" in the whole project to get them from the end of the settee onto the floor by the companionway. From there the same 4-part block and tackle hung from the boom got them onto the cockpit floor. I have an outboard crane on the transom from which the same block and tackle lowered the batteries from the cockpit onto the ground below. (I was in the yard for a bottom job at the time.) None of it was fun, but all of it was doable by myself, and I'm definitely not a muscle man.
I'll admit I was very happy when the yard manager agreed to have one of his guys lift the new batteries up to the cockpit using the yard's lift truck. From there it was the same steps in reverse to get them back under the settee.
When these batteries die, I'll probably replace them with 4 smaller 6V golf cart batteries. But with some planning, you can do just about anything if you need to.