What you have here is a real problem, being a plastic like surface, this is usually fibreglass or close to fibreglass, You really can not use the normal removers on this coating because they will have an adverse affect on the stability of the fibreglass, In fact it may soften up the surface to a point of becoming putty like. Some of the Enviromentally friendly removers may work, something like citristrip or 3m Safest stripper, however they may take forever and may not be aggresive enough to remove the epoxy. Mechanical means of removal are basicly out of the question since this will scratch the surface. The truth be told, these surfaces were never intended to be coated, they were designed to be left alone as the manufacturer intended. You may want to check with a marine supply store to see if they have a stripper that will remove coatings without harming the fibreglass.