I know that Porta-Bote has come out with a flat transom model in the last 8
years or so.

I have heard that it does well with a outboard motor ( I don't know what
size)..

The original 'canoe' like Porta-Bote was certainly capable of carrying two
people plus their gear.. A few cruiser used them and I know how much load a
cruiser might load (fuel and water cans, etc.).

To be honest, I have never heard of anyone compalaining about lack of load
carrying capacity.

I'm sure the would handle your intented use on Lake Washington.

--
My opinion and experience. FWIW

Steve
s/v Good Intentions