We run a 135 as well on a yacht, moving platform most of the time, and all our approaches and departures are Class 1. Our pad is the minimum dimensions the designer could get away with (but fully rated - never have worked that one out!!) and plus we normally have turbulence from the accommodation and heat from generator engine exhausts to contend with.
As a side bar I saw an EMS 135 in Devon a few years try to land in a field next to a car & motorcycle accident and he had to bail out as it was too steep, and then only place left to land was on the road in a very tight area with cables and trees all around him, weather was very severe almost gale conditions, he tracked down the road towards us, down a hill, with tail into wind and slashing rain, plonked it right in front of me. The best bit of flying I ever seen!! In from high and fast with a fancy flare was never going to work that day!!