Pick up a copy of Gardner's "The Dory Book", lots of good designs and how to on the construction process. To keep the weight down, go with relatively thin glued lap ply construction and put a thin layer of glass on the outside and coat everything else with epoxy. Either a Swampscott or a Gunning dory would be my choice for the camping end of things. Stay away from the Bank dory, they're just too tender unless they're loaded up and then they're a bear to deal with. Don't dismiss cutting a outboard well for a 3-5 horse Brit Seagull or similar engine either - there's so little bottom on these boats that low horse motors scoot you along pretty good and sip the fuel.

Best of luck.

-Dave Hancock