I fitted Tru-Design valves and skin fittings on my B36(2002). This was the three sleeping cabin model where the heads was located port side just forward of the main cabin. Although the heads compartment was of an adequate size, fitting the valves and through hull skin fittings was not an easy task due to the physical size the valves and hose tails that were needed, and particularly on account of the shape and size of the hose tails. This called for a degree of lateral thinking in regard to the order in which the various parts were secured together. Essentially the hose elbow was connected to the valve body first, then the skin fitting was loosely put in place with the securing nut left screwed on, but very slack and not tightened. The valve body was put next to the inner end of the skin fitting, and with one person outside to screw the skin fitting into the valve body while a second person inside the boat gently pushed the valve body towards the inner end of the skin fitting while that fitting was being turned in the appropriate direction so that both valve and skin fitting were screwed together. once those two parts were fully secured to each other, then the loose securing nut for skin fitting which was already more or less in place, was tightened up to the inner side of the hull, but not before the hull area in way of the skin fitting had been given a squirt of sealant to ensure that the through hull would be water tight.
Yes, it did seem a cack handed way of doing things, but having already bought the Tru-Design fittings, and already removed the old valves and thro hulls, I was not about to throw in the towel without a bit of sideways thinking of a way to get everything into place. It worked, and I had a couple of years worth of use out of the system before I sold the boat.