From another big guy…
You know that if you are a skier, other skiers will refer to you as a Clydesdale? We are big, but still pretty, welcome to the barn.
When I started I had a heck of a time finding a boat that weight classed what I wanted in a price range I could take. 6’ 270± butt nekkid before breakfast, and I was multi day river tripping. Figure me, camping gear, paddle gear, and food, I would be overweight in a 300lb boat the instant I put a foot in. I ended up with a well used Sea Lion @ 22" wide and almost 18’ long. We had a tense relationship for a little while, and she has thrown me a couple times. I have dropped weight to a tad over 240 and it helps getting in and out of the cockpit, but I am still top heavy. More weight in the shoulders than the butt so she can go quick. Learn to brace. Once you get used to it and put a skirt on and start edging you get a lot more comfortable with a skinny boat. Dont be afraid of getting one, you can learn it and then you will have a hard time going back.
I think your main problem will be foredeck space for your feet. I run a 11 work boot and there are a lot of times I feel out of room in the foot area of the Sea Lion. I have used crocs, sandals, wet shoes, and the latest that worked pretty well was deck shoes. I just bought neoprene boots for a trip so we will see how that goes.