Gordon, anyone who asks such a question are likely to be a person that will do the job tastefully. It is your boat so the decision is yours, but as you asked, I will give you my thoughts: 1) don't do anythink that will affect the structural integrity of the boat. I know this is largely obvious, but don't forget that it is possible to attach structures to the hull frames that are too stiff which will lead to locallised higher stresses that will damage the hull. 2) use the best possible materials and fasteners so that your good work will live on and be enjoyed by future owners. If future owners enjoy the boat there is more chance that the boat as a whole will be cherished for many more years. 3) ensure that any structure you build into the inside does not restrict the circulation of air inside or behind such structures otherwise you will initiate rot. 4) do not glue any part or internal structure to the hull structure. This will ensure that any future modifications can be made without damaging the hull structure.