Hmm, noble project but being 600 miles from open water
seems to be the first hurdle. Where do you propose to build the raft? Perhaps CF advice
would help locate a "raft yard" where you can stockpile your raw materials then assemble the raft. I'm guessing this needs to be about a half acre worth of waterfront space, with a small building and electricity on site, habitable. Prime real estate in some places. And all within easy distance of a large supply of salvage
materials. Your design will likely evolve from the materials found, an organic approach, rather than from a set of plans for which you have to source specific items. Interesting combination of creative, engineering and sailing skills will be needed. I can see many starts, teardowns, and restarts as materials are found. I'd try to nail down as many variables as possible, to help tighten up the design focus. But if someone offers you a hundred sheets
of salvageable plywood
when you've already begun assembling a hundred plastic drums into a platform, what would you do? Me, I'd see about a Wharram
design, since someone very knowledgeable saves me from pretending to be a naval architect/sailing savvy. Better odds at survival once underway. Apologies to Huck Finn aficionados.