I agree that mat is by far stonger. However it is much harder to work with. It appears that your house is constructed of ¾ plywood. Therefore you already have given the vessel great strength. If it was my build I would therefore go with mat. Most likely two layers inside & out. The process will go faster and the look with some fairing compound will give a nice finish. Re-enforced Plastics is a good start. If you need a second opinion I would also talk to Warren at DynaGrout
http://dynagroutfiberglass.com/default.aspx?pageId=1