We have removed the decks off of several 5.8 Nacras over the years (and re glassed them back after the hull work) without any major problems. Basically you just have to "go slow". We insert a narrow bladed paint scraper between the hull and the deck at one point, and then work carefully around the seam, only moving along in small increments. If you try wedging in a chisel or try to "lift" too wide a section at one time you will fracture the gel coat or worse still the glass laminate as well, but if you are patient then it is quite a simple and successful operation. I am not sure about the lay-up of the decks in the states, but the Australian ones have never needed any reinforcing for the deck “hatches/lids”.