I am considering a used CLC Tred Avon. My paddling partner is 6’4" and 230 lbs. Will he be able to fit in the boat?
paddling for what conditions and how big are you?
The Tred Avon is a variation on a Cape Charles, not exactly the best design to pick if you're going into waves.
There are many s&g designs out there worth looking at. I assume you're going from plans if that design interests you.
The shortcoming of the original CLC designs is that they're an accomodation to a construction technique more than a design derived from paddling/testing/redesign for wind/waves. The first CLC four panels hulls had a lot of rocker and actually were very easily driven through the water. The problem with the designs is that the side panels are nearly a straight rectangle with a low bow and nearly symmetrical hull shape. The low bow and construction technique makes for fine ends and easy bow burying in waves. Nothing wrong with that if you aren't in waves over 1'.
The nearly symmetrical hull shape makes for moderate weathercocking.
On a bit more thought it would fit the big person, you might be tempted to give a bit more height to the deck beam. Instead of the stated radius make it an inch or two tigher radius. This is something you can easily do when the hull is built.
Assuming a rudder will be installed you can ignore the weathercocking attributes but the low bow would be worth addressing. I'd redraw the side panels with an extra 2" to the bow height.
If the deck panel can't accomodate the upturned sheer there's a couple ways to address it.
One is to go ahead and make a two piece deck like the Arctic Hawk going to a flat frong bulkhead. Nothing wrong with that solution.
If you like the one piece deck you can do what I did on a kayak with an upswept sheer.
Pre-glue a 1/4"x 1/4" 1/2 round piece of wood down the centerline. Then glass a bias strip of 4oz glass over that. When you put the deck on that glued on strip will prevent the deck from folding downward.
For the cost of making a big double with Okoume and epoxy you're going to be hitting close to $600. If you really want a nice big double for two 200lbs paddlers the Pygmy Osprey double kit is a much, much better design.