Hi Bilby

I think you'll find that theres not much you can do to bring the weight down, perhaps a new deck would save a little, but the older glass mossies with the timber decks are just heavier than boats can be built now, it won't be so much the timber aspect that the weight differs its more the fibreglass, which obviously you can't much with.

The best idea IMO would be replace the decks with gaboon, check out the inside while their off, repair/replace anything that looks suspect, you could, to neaten the appearance recess your tramp track into the hulls with a glass tube.

Sanding the hulls I would stop if at the glass, then fill any obvious hollows etc.. and then long board the hulls, but don't go any further through the glass! then primer and long board again to show up anymore imperfections and then again if neccessary until your happy to paint, you might find yourself doing it a few times, and I sometimes think it a waste of paint, sanding it off, but the end result will show off your hard work.

Keep us informed with the project, and photos please if you can. Theres heaps of people here that can help out with all sorts of things, and my method might be trumped by someone else, but anything from painting hulls to fitting masts to beach wheels someone will throw some ideas you way.

Have Fun

Regards